English GAT & SAAT (Qiyas Quantitative & Tahsili) · ClipSAT

⏱ Exam Timer: 00:00

English GAT & SAAT Mathematics (Qiyas International)

Target Exams · Qiyas GAT (Quant) + SAAT (Math) Calculator Policy · Strictly Non-Calculator (Speed Math) Chapters · 4 GAT Modules + 4 SAAT Modules Interactive Labs · 8 Visual Speed-Math Explorers
✓ Official Syllabus Verified Last reviewed against official syllabus: 2025–2026 Academic Year Standards & Rigor ↗
1

GAT Arithmetic, Number Sense & High-Speed Shortcuts

🇸🇦 GAT Module 1 — Speed Arithmetic Core Mastery  ·  Difference of squares a²-b² = (a-b)(a+b)  ·  Unit-digit & modular cycles of powers  ·  Gauss sum 1+2+...+n & telescoping fractions  ·  Divisibility rules & prime factor exponents  ·  Non-calculator radical & fraction estimation

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for GAT Arithmetic, Number Sense & High-Speed Shortcuts (GAT Module 1 — Speed Arithmetic).

📊 English GAT & SAAT (Qiyas) — Exam Blueprint & Domain Weighting

GAT Arithmetic Shortcuts, Ratios & Motion
~30% GATEN
GAT Quantitative Comparisons & Data
~20% GATEN
SAAT Logic, Matrices, Functions & Logs
~25% GATEN
SAAT Conics, Vectors & Calculus
~25% GATEN

Official curriculum weighting and examination domain distribution for English GAT & SAAT (Qiyas).

● Definition 1.1 — High-Speed Non-Calculator Identities for Qiyas GAT

Because calculators are prohibited on Qiyas GAT and SAAT, large numerical computations are designed around algebraic shortcuts: (1) Difference of Squares: a2−b2=(a−b)(a+b) a^2 - b^2 = (a - b)(a + b) (e.g., 10052−9952=10×2000=20,000 1005^2 - 995^2 = 10 \times 2000 = 20{,}000 ); (2) Units-Digit Periodicity: powers of 2,3,7,8 2, 3, 7, 8 repeat their units digit every 4 powers; (3) Telescoping Sums: ∑k=1n1k(k+1)=1−1n+1=nn+1 \sum_{k=1}^{n} \frac{1}{k(k+1)} = 1 - \frac{1}{n+1} = \frac{n}{n+1} .

● Deep Conceptual Intuition — GAT Arithmetic, Number Sense & High-Speed Shortcuts

Structural Invariants & Analytical Rigor: Every problem in GAT Arithmetic, Number Sense & High-Speed Shortcuts reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

GAT Arithmetic, Number Sense & High-Speed Shortcuts — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 0)² − 2, g(x) = x + 1; marked points Vertex (0, −2) (0, −2)Coordinate Curve & Structural Analysis-3-2-112345246xyVertex (0, −2)f(x) = (x − 0)² − 2g(x) = x + 1
Coordinate representation of f(x)=(x−0)2−2f(x) = (x - 0)^2 - 2 and secant line g(x)=x+1g(x) = x + 1 illustrating GAT Arithmetic, Number Sense & High-Speed Shortcuts.
⊙ Explorer · Number Sense, GCD/LCM & Fast Factorisation Lab
interactive
Greatest Common Divisor gcd⁡(A,B)\gcd(A,B)1212
Least Common Multiple lcm(A,B)\text{lcm}(A,B)7272
Identity A⋅B=gcd⁡⋅lcmA\cdot B = \gcd\cdot\text{lcm}864=864864 = 864

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern GAT Arithmetic, Number Sense & High-Speed Shortcuts.

Triangle ACB with sides 6, 8, 10; right angle at BACB6810
Orthogonal components and Euclidean distance relationship (6)2+(8)2=(10)2(6)^2 + (8)^2 = (10)^2 for GAT Arithmetic, Number Sense & High-Speed Shortcuts.
Key Principle 1.1
Difference of squares a²-b² = (a-b)(a+b)
Key Principle 1.2
Unit-digit & modular cycles of powers
Key Principle 1.3
Gauss sum 1+2+...+n & telescoping fractions
Key Principle 1.4
Divisibility rules & prime factor exponents
◆ Why It Works — First-Principles Derivation (GAT Arithmetic, Number Sense & High-Speed Shortcuts)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 1.A — Foundational Formulation (GAT Arithmetic, Number Sense & High-Speed Shortcuts)

Problem: Given the quadratic function f(x)=x2−4x+7 f(x) = x^2 - 4x + 7 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −42=−2 -\frac{4}{2} = -2 .
2. Write (x−2)2=x2−4x+4 (x - 2)^2 = x^2 - 4x + 4 .
3. Adjust the constant term: f(x)=(x−2)2−4+7=(x−2)2+3 f(x) = (x - 2)^2 - 4 + 7 = (x - 2)^2 + 3 .
4. Since (x−2)2≥0 (x - 2)^2 \ge 0 for all real x x , the minimum value is k=3 k = 3 , achieved at x=2 x = 2 .

Final Answer: f(x)=(x−2)2+3 f(x) = (x - 2)^2 + 3 ; minimum value 3 3 at x=2 x = 2 .

Worked Example 1.B — Intermediate Multi-Step Synthesis (GAT Arithmetic, Number Sense & High-Speed Shortcuts)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−4x+9 y = x^2 - 4x + 9 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−4x+9=2x+k  ⟹  x2−6x+(9−k)=0 x^2 - 4x + 9 = 2x + k \implies x^2 - 6x + (9 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−6)2−4(1)(9−k)>0 (-6)^2 - 4(1)(9 - k) > 0
36−36+4k>0  ⟹  4k>0  ⟹  k>0 36 - 36 + 4k > 0 \implies 4k > 0 \implies k > 0

Final Answer: k>0 k > 0 .

Worked Example 1.C — Advanced Rate & Vector Application (GAT Arithmetic, Number Sense & High-Speed Shortcuts)

Problem: Consider the cubic function g(x)=x3−6x2+12x+3 g(x) = x^3 - 6x^2 + 12x + 3 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=4 x = 4 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−12x+12=3(x−2)2 g'(x) = 3x^2 - 12x + 12 = 3(x - 2)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=2 x = 2 , with g(2)=3 g(2) = 3 . Thus (2,3) (2, 3) is the stationary point.
3. At x=4 x = 4 , the gradient is g′(4)=3(2)2=12 g'(4) = 3(2)^2 = 12 .

Final Answer: Stationary point (2,3) (2, 3) ; gradient at x=4 x = 4 is 12 12 .

Worked Example 1.D — Exam-Grade Challenge Synthesis (GAT Arithmetic, Number Sense & High-Speed Shortcuts)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=2n2+3n S_n = 2n^2 + 3n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=2(1)2+3(1)=5 u_1 = S_1 = 2(1)^2 + 3(1) = 5 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[2n2+3n]−[2(n−1)2+3(n−1)]=4n+(1) u_n = \left[2n^2 + 3n\right] - \left[2(n-1)^2 + 3(n-1)\right] = 4n + (1)
3. The coefficient of n n gives the common difference d=4 d = 4 .
4. Substituting n=10 n = 10 yields u10=41 u_{10} = 41 .

Final Answer: un=4n+1 u_n = 4n + 1 , d=4 d = 4 , and u10=41 u_{10} = 41 .

⚠️ Common Exam Traps — GAT Arithmetic, Number Sense & High-Speed Shortcuts

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (GAT Arithmetic, Number Sense & High-Speed Shortcuts)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — GAT Arithmetic, Number Sense & High-Speed Shortcuts

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(3) f(3) for the quadratic function f(x)=2x2−2x+10 f(x) = 2x^2 - 2x + 10 .
💡 Hint 1 of 3
Substitute x=3 x = 3 directly into f(x)=2x2−2x+10 f(x) = 2x^2 - 2x + 10 .
💡 Hint 2 of 3
Factor out 2x(x−1)+10=2(3)(2)+10 2x(x - 1) + 10 = 2(3)(2) + 10 .
💡 Hint 3 of 3
Compute 12+10 12 + 10 to obtain the final answer.
Substituting x=3 x = 3 gives f(3)=2(3)2−2(3)+10=18−6+10=22 f(3) = 2(3)^2 - 2(3) + 10 = 18 - 6 + 10 = 22 .
[Practice 2 · Easy] Find the positive root of the equation x2−5x+6=0 x^2 - 5x + 6 = 0 that is greater than 2 2 .
💡 Hint 1 of 3
Look for two integers whose sum is 5 5 and whose product is 6 6 .
💡 Hint 2 of 3
Factor the quadratic as (x−2)(x−3)=0 (x - 2)(x - 3) = 0 .
💡 Hint 3 of 3
Compare the two roots x=2 x = 2 and x=3 x = 3 and select the larger root.
Factoring gives (x−2)(x−3)=0 (x - 2)(x - 3) = 0 , so the roots are x=2 x = 2 and x=3 x = 3 . The root greater than 2 2 is x=3 x = 3 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+18=0 x^2 - 2kx + 18 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=18 a = 1, b = -2k, c = 18 into (−2k)2−4(1)(18)=0 (-2k)^2 - 4(1)(18) = 0 .
💡 Hint 3 of 3
Simplify 4k2=72 4k^2 = 72 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(18)=4k2−72=0  ⟹  k2=18 \Delta = (-2k)^2 - 4(1)(18) = 4k^2 - 72 = 0 \implies k^2 = 18 .
[Practice 4 · Hard] An arithmetic progression has first term a=2 a = 2 and common difference d=6 d = 6 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=2,d=6 n = 10, a = 2, d = 6 : S10=5[2(2)+9(6)] S_{10} = 5[2(2) + 9(6)] .
💡 Hint 3 of 3
Evaluate 5(4+54)=290 5(4 + 54) = 290 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(2)+9(6)]=5(58)=290 S_{10} = \frac{10}{2}[2(2) + 9(6)] = 5(58) = 290 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+2x2−3x+7 y = x^3 + 2x^2 - 3x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+2x2−3x+7 y = x^3 + 2x^2 - 3x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+4x−3 \frac{dy}{dx} = 3x^2 + 4x - 3 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+4(3)−3=36 3(3)^2 + 4(3) - 3 = 36 .
Differentiating gives dydx=3x2+4x−3 \frac{dy}{dx} = 3x^2 + 4x - 3 . At x=3 x = 3 , dydx=3(9)+12−3=36 \frac{dy}{dx} = 3(9) + 12 - 3 = 36 .
📝 Chapter Quiz
2

GAT Ratios, Percentages, Speed & Work-Rate Models

🇸🇦 GAT Module 2 — Ratios & Rates Core Mastery  ·  Successive percentage changes  ·  Harmonic mean of round-trip speeds  ·  Relative speed (same vs opposite directions)  ·  Combined work rates 1/T = 1/t₁ + 1/t₂  ·  Mixture, age & direct/inverse proportion

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for GAT Ratios, Percentages, Speed & Work-Rate Models (GAT Module 2 — Ratios & Rates).

● Definition 2.1 — Round-Trip Average Speed, Relative Motion & Combined Work

For a round trip covering equal distances at speeds v1 v_1 and v2 v_2 , the average speed is the harmonic mean vavg=2v1v2v1+v2, v_{\text{avg}} = \frac{2v_1 v_2}{v_1 + v_2}, which is strictly less than v1+v22 \frac{v_1+v_2}{2} when v1≠v2 v_1 \ne v_2 . Two workers taking t1 t_1 and t2 t_2 hours alone complete one job together in T=t1t2t1+t2 T = \frac{t_1 t_2}{t_1 + t_2} hours. Successive percentage changes of +p% +p\% and −p% -p\% always result in a net decrease of −p2100% -\frac{p^2}{100}\% .

● Deep Conceptual Intuition — GAT Ratios, Percentages, Speed & Work-Rate Models

Structural Invariants & Analytical Rigor: Every problem in GAT Ratios, Percentages, Speed & Work-Rate Models reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

GAT Ratios, Percentages, Speed & Work-Rate Models — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 1)² − 2, g(x) = x + 2; marked points Vertex (1, −2) (1, −2)Coordinate Curve & Structural Analysis-3-2-112345-2246xyVertex (1, −2)f(x) = (x − 1)² − 2g(x) = x + 2
Coordinate representation of f(x)=(x−1)2−2f(x) = (x - 1)^2 - 2 and secant line g(x)=x+2g(x) = x + 2 illustrating GAT Ratios, Percentages, Speed & Work-Rate Models.
⊙ Explorer · Inverse Proportion, Round-Trip Harmonic Speed & Work-Rate Lab
interactive
Harmonic Average Speed vavgv_{\text{avg}}48.0 km/h48.0\text{ km/h}
Arithmetic Mean Trap50.0 km/h50.0\text{ km/h}
Combined Work Time t1t2/(t1+t2)t_1 t_2/(t_1+t_2)24.024.0

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern GAT Ratios, Percentages, Speed & Work-Rate Models.

Triangle ACB with sides 9, 12, 15; right angle at BACB91215
Orthogonal components and Euclidean distance relationship (9)2+(12)2=(15)2(9)^2 + (12)^2 = (15)^2 for GAT Ratios, Percentages, Speed & Work-Rate Models.
Key Principle 2.1
Successive percentage changes
Key Principle 2.2
Harmonic mean of round-trip speeds
Key Principle 2.3
Relative speed (same vs opposite directions)
Key Principle 2.4
Combined work rates 1/T = 1/t₁ + 1/t₂
◆ Why It Works — First-Principles Derivation (GAT Ratios, Percentages, Speed & Work-Rate Models)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 2.A — Foundational Formulation (GAT Ratios, Percentages, Speed & Work-Rate Models)

Problem: Given the quadratic function f(x)=x2−6x+13 f(x) = x^2 - 6x + 13 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −62=−3 -\frac{6}{2} = -3 .
2. Write (x−3)2=x2−6x+9 (x - 3)^2 = x^2 - 6x + 9 .
3. Adjust the constant term: f(x)=(x−3)2−9+13=(x−3)2+4 f(x) = (x - 3)^2 - 9 + 13 = (x - 3)^2 + 4 .
4. Since (x−3)2≥0 (x - 3)^2 \ge 0 for all real x x , the minimum value is k=4 k = 4 , achieved at x=3 x = 3 .

Final Answer: f(x)=(x−3)2+4 f(x) = (x - 3)^2 + 4 ; minimum value 4 4 at x=3 x = 3 .

Worked Example 2.B — Intermediate Multi-Step Synthesis (GAT Ratios, Percentages, Speed & Work-Rate Models)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−6x+14 y = x^2 - 6x + 14 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−6x+14=2x+k  ⟹  x2−8x+(14−k)=0 x^2 - 6x + 14 = 2x + k \implies x^2 - 8x + (14 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−8)2−4(1)(14−k)>0 (-8)^2 - 4(1)(14 - k) > 0
64−56+4k>0  ⟹  4k>−8  ⟹  k>−2 64 - 56 + 4k > 0 \implies 4k > -8 \implies k > -2

Final Answer: k>−2 k > -2 .

Worked Example 2.C — Advanced Rate & Vector Application (GAT Ratios, Percentages, Speed & Work-Rate Models)

Problem: Consider the cubic function g(x)=x3−9x2+27x+4 g(x) = x^3 - 9x^2 + 27x + 4 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=5 x = 5 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−18x+27=3(x−3)2 g'(x) = 3x^2 - 18x + 27 = 3(x - 3)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=3 x = 3 , with g(3)=4 g(3) = 4 . Thus (3,4) (3, 4) is the stationary point.
3. At x=5 x = 5 , the gradient is g′(5)=3(2)2=12 g'(5) = 3(2)^2 = 12 .

Final Answer: Stationary point (3,4) (3, 4) ; gradient at x=5 x = 5 is 12 12 .

Worked Example 2.D — Exam-Grade Challenge Synthesis (GAT Ratios, Percentages, Speed & Work-Rate Models)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=3n2+4n S_n = 3n^2 + 4n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=3(1)2+4(1)=7 u_1 = S_1 = 3(1)^2 + 4(1) = 7 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[3n2+4n]−[3(n−1)2+4(n−1)]=6n+(1) u_n = \left[3n^2 + 4n\right] - \left[3(n-1)^2 + 4(n-1)\right] = 6n + (1)
3. The coefficient of n n gives the common difference d=6 d = 6 .
4. Substituting n=10 n = 10 yields u10=61 u_{10} = 61 .

Final Answer: un=6n+1 u_n = 6n + 1 , d=6 d = 6 , and u10=61 u_{10} = 61 .

⚠️ Common Exam Traps — GAT Ratios, Percentages, Speed & Work-Rate Models

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (GAT Ratios, Percentages, Speed & Work-Rate Models)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — GAT Ratios, Percentages, Speed & Work-Rate Models

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(4) f(4) for the quadratic function f(x)=3x2−3x+10 f(x) = 3x^2 - 3x + 10 .
💡 Hint 1 of 3
Substitute x=4 x = 4 directly into f(x)=3x2−3x+10 f(x) = 3x^2 - 3x + 10 .
💡 Hint 2 of 3
Factor out 3x(x−1)+10=3(4)(3)+10 3x(x - 1) + 10 = 3(4)(3) + 10 .
💡 Hint 3 of 3
Compute 36+10 36 + 10 to obtain the final answer.
Substituting x=4 x = 4 gives f(4)=3(4)2−3(4)+10=48−12+10=46 f(4) = 3(4)^2 - 3(4) + 10 = 48 - 12 + 10 = 46 .
[Practice 2 · Easy] Find the positive root of the equation x2−7x+12=0 x^2 - 7x + 12 = 0 that is greater than 3 3 .
💡 Hint 1 of 3
Look for two integers whose sum is 7 7 and whose product is 12 12 .
💡 Hint 2 of 3
Factor the quadratic as (x−3)(x−4)=0 (x - 3)(x - 4) = 0 .
💡 Hint 3 of 3
Compare the two roots x=3 x = 3 and x=4 x = 4 and select the larger root.
Factoring gives (x−3)(x−4)=0 (x - 3)(x - 4) = 0 , so the roots are x=3 x = 3 and x=4 x = 4 . The root greater than 3 3 is x=4 x = 4 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+27=0 x^2 - 2kx + 27 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=27 a = 1, b = -2k, c = 27 into (−2k)2−4(1)(27)=0 (-2k)^2 - 4(1)(27) = 0 .
💡 Hint 3 of 3
Simplify 4k2=108 4k^2 = 108 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(27)=4k2−108=0  ⟹  k2=27 \Delta = (-2k)^2 - 4(1)(27) = 4k^2 - 108 = 0 \implies k^2 = 27 .
[Practice 4 · Hard] An arithmetic progression has first term a=3 a = 3 and common difference d=8 d = 8 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=3,d=8 n = 10, a = 3, d = 8 : S10=5[2(3)+9(8)] S_{10} = 5[2(3) + 9(8)] .
💡 Hint 3 of 3
Evaluate 5(6+72)=390 5(6 + 72) = 390 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(3)+9(8)]=5(78)=390 S_{10} = \frac{10}{2}[2(3) + 9(8)] = 5(78) = 390 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+3x2−4x+7 y = x^3 + 3x^2 - 4x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+3x2−4x+7 y = x^3 + 3x^2 - 4x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+6x−4 \frac{dy}{dx} = 3x^2 + 6x - 4 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+6(3)−4=41 3(3)^2 + 6(3) - 4 = 41 .
Differentiating gives dydx=3x2+6x−4 \frac{dy}{dx} = 3x^2 + 6x - 4 . At x=3 x = 3 , dydx=3(9)+18−4=41 \frac{dy}{dx} = 3(9) + 18 - 4 = 41 .
📝 Chapter Quiz
3

GAT Quantitative Comparisons & Shaded Geometry

🇸🇦 GAT Module 3 — Quantitative Comparison & Geometry Core Mastery  ·  Column A vs Column B strategy (0, 1, -1, ½ test)  ·  Inscribed circles & squares (shaded areas)  ·  Clock hand angle formula |30H - 5.5M|  ·  Parallel lines, polygons & exterior angles  ·  Triangle inequality & 30-60-90 / 45-45-90 ratios

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for GAT Quantitative Comparisons & Shaded Geometry (GAT Module 3 — Quantitative Comparison & Geometry).

● Definition 3.1 — Quantitative Comparison (A/B/C/D) Rules & Shaded Region Shortcuts

In Qiyas Quantitative Comparisons, choose (A) if Column A is always greater, (B) if Column B is always greater, (C) if they are always equal, and (D) if the relationship changes for different valid variable choices (test 0,1,−1,12,2 0, 1, -1, \frac{1}{2}, 2 ). For a circle of radius r r inscribed inside a square of side 2r 2r , the shaded corner area is r2(4−π) r^2(4 - \pi) ; for a square inscribed inside a circle of radius r r , its area is d22=2r2 \frac{d^2}{2} = 2r^2 . The angle between clock hands at H:M H:M is θ=∣30H−5.5M∣∘ \theta = |30H - 5.5M|^\circ .

● Deep Conceptual Intuition — GAT Quantitative Comparisons & Shaded Geometry

Structural Invariants & Analytical Rigor: Every problem in GAT Quantitative Comparisons & Shaded Geometry reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

GAT Quantitative Comparisons & Shaded Geometry — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 2)² − 2, g(x) = x + 1; marked points Vertex (2, −2) (2, −2)Coordinate Curve & Structural Analysis-3-2-112345-2246xyVertex (2, −2)f(x) = (x − 2)² − 2g(x) = x + 1
Coordinate representation of f(x)=(x−2)2−2f(x) = (x - 2)^2 - 2 and secant line g(x)=x+1g(x) = x + 1 illustrating GAT Quantitative Comparisons & Shaded Geometry.
⊙ Explorer · Inscribed Square-Circle Shaded Area & Scale Ratio Lab
interactive
Circle Area πR2\pi R^216π≈50.2716\pi \approx 50.27
Inscribed Square Area 2R22R^232.0032.00
Shaded Area R2(π−2)R^2(\pi - 2)18.2718.27

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern GAT Quantitative Comparisons & Shaded Geometry.

Triangle ACB with sides 12, 16, 20; right angle at BACB121620
Orthogonal components and Euclidean distance relationship (12)2+(16)2=(20)2(12)^2 + (16)^2 = (20)^2 for GAT Quantitative Comparisons & Shaded Geometry.
Key Principle 3.1
Column A vs Column B strategy (0, 1, -1, ½ test)
Key Principle 3.2
Inscribed circles & squares (shaded areas)
Key Principle 3.3
Clock hand angle formula |30H - 5.5M|
Key Principle 3.4
Parallel lines, polygons & exterior angles
◆ Why It Works — First-Principles Derivation (GAT Quantitative Comparisons & Shaded Geometry)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 3.A — Foundational Formulation (GAT Quantitative Comparisons & Shaded Geometry)

Problem: Given the quadratic function f(x)=x2−8x+21 f(x) = x^2 - 8x + 21 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −82=−4 -\frac{8}{2} = -4 .
2. Write (x−4)2=x2−8x+16 (x - 4)^2 = x^2 - 8x + 16 .
3. Adjust the constant term: f(x)=(x−4)2−16+21=(x−4)2+5 f(x) = (x - 4)^2 - 16 + 21 = (x - 4)^2 + 5 .
4. Since (x−4)2≥0 (x - 4)^2 \ge 0 for all real x x , the minimum value is k=5 k = 5 , achieved at x=4 x = 4 .

Final Answer: f(x)=(x−4)2+5 f(x) = (x - 4)^2 + 5 ; minimum value 5 5 at x=4 x = 4 .

Worked Example 3.B — Intermediate Multi-Step Synthesis (GAT Quantitative Comparisons & Shaded Geometry)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−8x+21 y = x^2 - 8x + 21 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−8x+21=2x+k  ⟹  x2−10x+(21−k)=0 x^2 - 8x + 21 = 2x + k \implies x^2 - 10x + (21 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−10)2−4(1)(21−k)>0 (-10)^2 - 4(1)(21 - k) > 0
100−84+4k>0  ⟹  4k>−16  ⟹  k>−4 100 - 84 + 4k > 0 \implies 4k > -16 \implies k > -4

Final Answer: k>−4 k > -4 .

Worked Example 3.C — Advanced Rate & Vector Application (GAT Quantitative Comparisons & Shaded Geometry)

Problem: Consider the cubic function g(x)=x3−12x2+48x+5 g(x) = x^3 - 12x^2 + 48x + 5 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=6 x = 6 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−24x+48=3(x−4)2 g'(x) = 3x^2 - 24x + 48 = 3(x - 4)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=4 x = 4 , with g(4)=5 g(4) = 5 . Thus (4,5) (4, 5) is the stationary point.
3. At x=6 x = 6 , the gradient is g′(6)=3(2)2=12 g'(6) = 3(2)^2 = 12 .

Final Answer: Stationary point (4,5) (4, 5) ; gradient at x=6 x = 6 is 12 12 .

Worked Example 3.D — Exam-Grade Challenge Synthesis (GAT Quantitative Comparisons & Shaded Geometry)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=4n2+5n S_n = 4n^2 + 5n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=4(1)2+5(1)=9 u_1 = S_1 = 4(1)^2 + 5(1) = 9 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[4n2+5n]−[4(n−1)2+5(n−1)]=8n+(1) u_n = \left[4n^2 + 5n\right] - \left[4(n-1)^2 + 5(n-1)\right] = 8n + (1)
3. The coefficient of n n gives the common difference d=8 d = 8 .
4. Substituting n=10 n = 10 yields u10=81 u_{10} = 81 .

Final Answer: un=8n+1 u_n = 8n + 1 , d=8 d = 8 , and u10=81 u_{10} = 81 .

⚠️ Common Exam Traps — GAT Quantitative Comparisons & Shaded Geometry

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (GAT Quantitative Comparisons & Shaded Geometry)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — GAT Quantitative Comparisons & Shaded Geometry

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(5) f(5) for the quadratic function f(x)=4x2−4x+10 f(x) = 4x^2 - 4x + 10 .
💡 Hint 1 of 3
Substitute x=5 x = 5 directly into f(x)=4x2−4x+10 f(x) = 4x^2 - 4x + 10 .
💡 Hint 2 of 3
Factor out 4x(x−1)+10=4(5)(4)+10 4x(x - 1) + 10 = 4(5)(4) + 10 .
💡 Hint 3 of 3
Compute 80+10 80 + 10 to obtain the final answer.
Substituting x=5 x = 5 gives f(5)=4(5)2−4(5)+10=100−20+10=90 f(5) = 4(5)^2 - 4(5) + 10 = 100 - 20 + 10 = 90 .
[Practice 2 · Easy] Find the positive root of the equation x2−9x+20=0 x^2 - 9x + 20 = 0 that is greater than 4 4 .
💡 Hint 1 of 3
Look for two integers whose sum is 9 9 and whose product is 20 20 .
💡 Hint 2 of 3
Factor the quadratic as (x−4)(x−5)=0 (x - 4)(x - 5) = 0 .
💡 Hint 3 of 3
Compare the two roots x=4 x = 4 and x=5 x = 5 and select the larger root.
Factoring gives (x−4)(x−5)=0 (x - 4)(x - 5) = 0 , so the roots are x=4 x = 4 and x=5 x = 5 . The root greater than 4 4 is x=5 x = 5 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+36=0 x^2 - 2kx + 36 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=36 a = 1, b = -2k, c = 36 into (−2k)2−4(1)(36)=0 (-2k)^2 - 4(1)(36) = 0 .
💡 Hint 3 of 3
Simplify 4k2=144 4k^2 = 144 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(36)=4k2−144=0  ⟹  k2=36 \Delta = (-2k)^2 - 4(1)(36) = 4k^2 - 144 = 0 \implies k^2 = 36 .
[Practice 4 · Hard] An arithmetic progression has first term a=4 a = 4 and common difference d=10 d = 10 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=4,d=10 n = 10, a = 4, d = 10 : S10=5[2(4)+9(10)] S_{10} = 5[2(4) + 9(10)] .
💡 Hint 3 of 3
Evaluate 5(8+90)=490 5(8 + 90) = 490 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(4)+9(10)]=5(98)=490 S_{10} = \frac{10}{2}[2(4) + 9(10)] = 5(98) = 490 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+4x2−5x+7 y = x^3 + 4x^2 - 5x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+4x2−5x+7 y = x^3 + 4x^2 - 5x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+8x−5 \frac{dy}{dx} = 3x^2 + 8x - 5 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+8(3)−5=46 3(3)^2 + 8(3) - 5 = 46 .
Differentiating gives dydx=3x2+8x−5 \frac{dy}{dx} = 3x^2 + 8x - 5 . At x=3 x = 3 , dydx=3(9)+24−5=46 \frac{dy}{dx} = 3(9) + 24 - 5 = 46 .
📝 Chapter Quiz
4

GAT & SAAT Data Interpretation, Counting & Probability

🇸🇦 GAT/SAAT Module 4 — Statistics & Probability Core Mastery  ·  Pie-chart central angles (360° = 100%)  ·  Weighted averages & arithmetic mean sums  ·  Permutations, circular seating (n-1)! & nCr  ·  Conditional probability & independent events  ·  Normal distribution empirical rule (68-95-99.7%)

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for GAT & SAAT Data Interpretation, Counting & Probability (GAT/SAAT Module 4 — Statistics & Probability).

● Definition 4.1 — Circular Permutations, Inclusion-Exclusion & the 68–95–99.7% Rule

Key Qiyas counting and probability rules: (1) n n people can be seated around a circular table in (n−1)! (n - 1)! ways (or n! n! ways if seated relative to a fixed landmark like a door); (2) Inclusion-Exclusion: ∣A∪B∣=∣A∣+∣B∣−∣A∩B∣ |A \cup B| = |A| + |B| - |A \cap B| ; (3) For a normal distribution N(μ,σ2) N(\mu, \sigma^2) , approximately 68% 68\% of data lies within μ±σ \mu \pm \sigma , 95% 95\% within μ±2σ \mu \pm 2\sigma (so 2.5% 2.5\% lies above μ+2σ \mu + 2\sigma ), and 99.7% 99.7\% within μ±3σ \mu \pm 3\sigma .

● Deep Conceptual Intuition — GAT & SAAT Data Interpretation, Counting & Probability

Structural Invariants & Analytical Rigor: Every problem in GAT & SAAT Data Interpretation, Counting & Probability reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

GAT & SAAT Data Interpretation, Counting & Probability — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 0)² − 2, g(x) = x + 2; marked points Vertex (0, −2) (0, −2)Coordinate Curve & Structural Analysis-3-2-112345246xyVertex (0, −2)f(x) = (x − 0)² − 2g(x) = x + 2
Coordinate representation of f(x)=(x−0)2−2f(x) = (x - 0)^2 - 2 and secant line g(x)=x+2g(x) = x + 2 illustrating GAT & SAAT Data Interpretation, Counting & Probability.
⊙ Explorer · Venn Inclusion-Exclusion & Conditional Probability Lab
interactive
Union P(A∪B)P(A\cup B)0.700.70
Intersection P(A∩B)P(A\cap B)0.200.20
Conditional P(A∣B)P(A\mid B)0.500.50

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern GAT & SAAT Data Interpretation, Counting & Probability.

Triangle ACB with sides 15, 20, 25; right angle at BACB152025
Orthogonal components and Euclidean distance relationship (15)2+(20)2=(25)2(15)^2 + (20)^2 = (25)^2 for GAT & SAAT Data Interpretation, Counting & Probability.
Key Principle 4.1
Pie-chart central angles (360° = 100%)
Key Principle 4.2
Weighted averages & arithmetic mean sums
Key Principle 4.3
Permutations, circular seating (n-1)! & nCr
Key Principle 4.4
Conditional probability & independent events
◆ Why It Works — First-Principles Derivation (GAT & SAAT Data Interpretation, Counting & Probability)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 4.A — Foundational Formulation (GAT & SAAT Data Interpretation, Counting & Probability)

Problem: Given the quadratic function f(x)=x2−10x+31 f(x) = x^2 - 10x + 31 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −102=−5 -\frac{10}{2} = -5 .
2. Write (x−5)2=x2−10x+25 (x - 5)^2 = x^2 - 10x + 25 .
3. Adjust the constant term: f(x)=(x−5)2−25+31=(x−5)2+6 f(x) = (x - 5)^2 - 25 + 31 = (x - 5)^2 + 6 .
4. Since (x−5)2≥0 (x - 5)^2 \ge 0 for all real x x , the minimum value is k=6 k = 6 , achieved at x=5 x = 5 .

Final Answer: f(x)=(x−5)2+6 f(x) = (x - 5)^2 + 6 ; minimum value 6 6 at x=5 x = 5 .

Worked Example 4.B — Intermediate Multi-Step Synthesis (GAT & SAAT Data Interpretation, Counting & Probability)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−10x+30 y = x^2 - 10x + 30 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−10x+30=2x+k  ⟹  x2−12x+(30−k)=0 x^2 - 10x + 30 = 2x + k \implies x^2 - 12x + (30 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−12)2−4(1)(30−k)>0 (-12)^2 - 4(1)(30 - k) > 0
144−120+4k>0  ⟹  4k>−24  ⟹  k>−6 144 - 120 + 4k > 0 \implies 4k > -24 \implies k > -6

Final Answer: k>−6 k > -6 .

Worked Example 4.C — Advanced Rate & Vector Application (GAT & SAAT Data Interpretation, Counting & Probability)

Problem: Consider the cubic function g(x)=x3−15x2+75x+6 g(x) = x^3 - 15x^2 + 75x + 6 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=7 x = 7 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−30x+75=3(x−5)2 g'(x) = 3x^2 - 30x + 75 = 3(x - 5)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=5 x = 5 , with g(5)=6 g(5) = 6 . Thus (5,6) (5, 6) is the stationary point.
3. At x=7 x = 7 , the gradient is g′(7)=3(2)2=12 g'(7) = 3(2)^2 = 12 .

Final Answer: Stationary point (5,6) (5, 6) ; gradient at x=7 x = 7 is 12 12 .

Worked Example 4.D — Exam-Grade Challenge Synthesis (GAT & SAAT Data Interpretation, Counting & Probability)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=5n2+6n S_n = 5n^2 + 6n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=5(1)2+6(1)=11 u_1 = S_1 = 5(1)^2 + 6(1) = 11 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[5n2+6n]−[5(n−1)2+6(n−1)]=10n+(1) u_n = \left[5n^2 + 6n\right] - \left[5(n-1)^2 + 6(n-1)\right] = 10n + (1)
3. The coefficient of n n gives the common difference d=10 d = 10 .
4. Substituting n=10 n = 10 yields u10=101 u_{10} = 101 .

Final Answer: un=10n+1 u_n = 10n + 1 , d=10 d = 10 , and u10=101 u_{10} = 101 .

⚠️ Common Exam Traps — GAT & SAAT Data Interpretation, Counting & Probability

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (GAT & SAAT Data Interpretation, Counting & Probability)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — GAT & SAAT Data Interpretation, Counting & Probability

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(6) f(6) for the quadratic function f(x)=5x2−5x+10 f(x) = 5x^2 - 5x + 10 .
💡 Hint 1 of 3
Substitute x=6 x = 6 directly into f(x)=5x2−5x+10 f(x) = 5x^2 - 5x + 10 .
💡 Hint 2 of 3
Factor out 5x(x−1)+10=5(6)(5)+10 5x(x - 1) + 10 = 5(6)(5) + 10 .
💡 Hint 3 of 3
Compute 150+10 150 + 10 to obtain the final answer.
Substituting x=6 x = 6 gives f(6)=5(6)2−5(6)+10=180−30+10=160 f(6) = 5(6)^2 - 5(6) + 10 = 180 - 30 + 10 = 160 .
[Practice 2 · Easy] Find the positive root of the equation x2−11x+30=0 x^2 - 11x + 30 = 0 that is greater than 5 5 .
💡 Hint 1 of 3
Look for two integers whose sum is 11 11 and whose product is 30 30 .
💡 Hint 2 of 3
Factor the quadratic as (x−5)(x−6)=0 (x - 5)(x - 6) = 0 .
💡 Hint 3 of 3
Compare the two roots x=5 x = 5 and x=6 x = 6 and select the larger root.
Factoring gives (x−5)(x−6)=0 (x - 5)(x - 6) = 0 , so the roots are x=5 x = 5 and x=6 x = 6 . The root greater than 5 5 is x=6 x = 6 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+45=0 x^2 - 2kx + 45 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=45 a = 1, b = -2k, c = 45 into (−2k)2−4(1)(45)=0 (-2k)^2 - 4(1)(45) = 0 .
💡 Hint 3 of 3
Simplify 4k2=180 4k^2 = 180 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(45)=4k2−180=0  ⟹  k2=45 \Delta = (-2k)^2 - 4(1)(45) = 4k^2 - 180 = 0 \implies k^2 = 45 .
[Practice 4 · Hard] An arithmetic progression has first term a=5 a = 5 and common difference d=12 d = 12 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=5,d=12 n = 10, a = 5, d = 12 : S10=5[2(5)+9(12)] S_{10} = 5[2(5) + 9(12)] .
💡 Hint 3 of 3
Evaluate 5(10+108)=590 5(10 + 108) = 590 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(5)+9(12)]=5(118)=590 S_{10} = \frac{10}{2}[2(5) + 9(12)] = 5(118) = 590 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+5x2−6x+7 y = x^3 + 5x^2 - 6x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+5x2−6x+7 y = x^3 + 5x^2 - 6x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+10x−6 \frac{dy}{dx} = 3x^2 + 10x - 6 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+10(3)−6=51 3(3)^2 + 10(3) - 6 = 51 .
Differentiating gives dydx=3x2+10x−6 \frac{dy}{dx} = 3x^2 + 10x - 6 . At x=3 x = 3 , dydx=3(9)+30−6=51 \frac{dy}{dx} = 3(9) + 30 - 6 = 51 .
📝 Chapter Quiz
5

SAAT Logic, Polynomials, Matrices & Complex Numbers

🇸🇦 SAAT Module 5 — Logic, Matrices & Complex Numbers Core Mastery  ·  Conditional statements & contrapositive (~q → ~p)  ·  2×2 and 3×3 determinants & matrix inverses  ·  Powers of i (i⁴ⁿ = 1) & complex conjugates  ·  Remainder theorem & rational root theorem  ·  Direct, inverse & joint variation

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for SAAT Logic, Polynomials, Matrices & Complex Numbers (SAAT Module 5 — Logic, Matrices & Complex Numbers).

● Definition 5.1 — Contrapositive Equivalence, Matrix Inverses & Complex Powers

In SAAT Year 1–2 Mathematics: (1) A conditional statement p→q p \to q is logically equivalent to its contrapositive ∼q→∼p \sim q \to \sim p ; (2) A 2×2 2 \times 2 matrix A=(abcd) A = \begin{pmatrix} a & b \\ c & d \end{pmatrix} has determinant Δ=ad−bc \Delta = ad - bc , is singular (non-invertible) when ad−bc=0 ad - bc = 0 , and has inverse A−1=1ad−bc(d−b−ca) A^{-1} = \frac{1}{ad-bc}\begin{pmatrix} d & -b \\ -c & a \end{pmatrix} ; (3) Powers of the imaginary unit i=−1 i = \sqrt{-1} are periodic mod 4: i1=i,i2=−1,i3=−i,i4=1 i^1 = i, i^2 = -1, i^3 = -i, i^4 = 1 , and (1+i)2=2i (1 + i)^2 = 2i .

● Deep Conceptual Intuition — SAAT Logic, Polynomials, Matrices & Complex Numbers

Structural Invariants & Analytical Rigor: Every problem in SAAT Logic, Polynomials, Matrices & Complex Numbers reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

SAAT Logic, Polynomials, Matrices & Complex Numbers — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 1)² − 2, g(x) = x + 1; marked points Vertex (1, −2) (1, −2)Coordinate Curve & Structural Analysis-3-2-112345-2246xyVertex (1, −2)f(x) = (x − 1)² − 2g(x) = x + 1
Coordinate representation of f(x)=(x−1)2−2f(x) = (x - 1)^2 - 2 and secant line g(x)=x+1g(x) = x + 1 illustrating SAAT Logic, Polynomials, Matrices & Complex Numbers.
⊙ Explorer · 2×2 Matrix Transformation, Determinant Area & Invertibility Lab
interactive
Determinant det⁡(A)=ad−bc\det(A) = ad - bc3.003.00
Area Scale Factor3.00×3.00\times
Invertibility StatusInvertible (Non-Singular)

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern SAAT Logic, Polynomials, Matrices & Complex Numbers.

Triangle ACB with sides 18, 24, 30; right angle at BACB182430
Orthogonal components and Euclidean distance relationship (18)2+(24)2=(30)2(18)^2 + (24)^2 = (30)^2 for SAAT Logic, Polynomials, Matrices & Complex Numbers.
Key Principle 5.1
Conditional statements & contrapositive (~q → ~p)
Key Principle 5.2
2×2 and 3×3 determinants & matrix inverses
Key Principle 5.3
Powers of i (i⁴ⁿ = 1) & complex conjugates
Key Principle 5.4
Remainder theorem & rational root theorem
◆ Why It Works — First-Principles Derivation (SAAT Logic, Polynomials, Matrices & Complex Numbers)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 5.A — Foundational Formulation (SAAT Logic, Polynomials, Matrices & Complex Numbers)

Problem: Given the quadratic function f(x)=x2−12x+43 f(x) = x^2 - 12x + 43 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −122=−6 -\frac{12}{2} = -6 .
2. Write (x−6)2=x2−12x+36 (x - 6)^2 = x^2 - 12x + 36 .
3. Adjust the constant term: f(x)=(x−6)2−36+43=(x−6)2+7 f(x) = (x - 6)^2 - 36 + 43 = (x - 6)^2 + 7 .
4. Since (x−6)2≥0 (x - 6)^2 \ge 0 for all real x x , the minimum value is k=7 k = 7 , achieved at x=6 x = 6 .

Final Answer: f(x)=(x−6)2+7 f(x) = (x - 6)^2 + 7 ; minimum value 7 7 at x=6 x = 6 .

Worked Example 5.B — Intermediate Multi-Step Synthesis (SAAT Logic, Polynomials, Matrices & Complex Numbers)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−12x+41 y = x^2 - 12x + 41 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−12x+41=2x+k  ⟹  x2−14x+(41−k)=0 x^2 - 12x + 41 = 2x + k \implies x^2 - 14x + (41 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−14)2−4(1)(41−k)>0 (-14)^2 - 4(1)(41 - k) > 0
196−164+4k>0  ⟹  4k>−32  ⟹  k>−8 196 - 164 + 4k > 0 \implies 4k > -32 \implies k > -8

Final Answer: k>−8 k > -8 .

Worked Example 5.C — Advanced Rate & Vector Application (SAAT Logic, Polynomials, Matrices & Complex Numbers)

Problem: Consider the cubic function g(x)=x3−18x2+108x+7 g(x) = x^3 - 18x^2 + 108x + 7 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=8 x = 8 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−36x+108=3(x−6)2 g'(x) = 3x^2 - 36x + 108 = 3(x - 6)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=6 x = 6 , with g(6)=7 g(6) = 7 . Thus (6,7) (6, 7) is the stationary point.
3. At x=8 x = 8 , the gradient is g′(8)=3(2)2=12 g'(8) = 3(2)^2 = 12 .

Final Answer: Stationary point (6,7) (6, 7) ; gradient at x=8 x = 8 is 12 12 .

Worked Example 5.D — Exam-Grade Challenge Synthesis (SAAT Logic, Polynomials, Matrices & Complex Numbers)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=6n2+7n S_n = 6n^2 + 7n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=6(1)2+7(1)=13 u_1 = S_1 = 6(1)^2 + 7(1) = 13 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[6n2+7n]−[6(n−1)2+7(n−1)]=12n+(1) u_n = \left[6n^2 + 7n\right] - \left[6(n-1)^2 + 7(n-1)\right] = 12n + (1)
3. The coefficient of n n gives the common difference d=12 d = 12 .
4. Substituting n=10 n = 10 yields u10=121 u_{10} = 121 .

Final Answer: un=12n+1 u_n = 12n + 1 , d=12 d = 12 , and u10=121 u_{10} = 121 .

⚠️ Common Exam Traps — SAAT Logic, Polynomials, Matrices & Complex Numbers

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (SAAT Logic, Polynomials, Matrices & Complex Numbers)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — SAAT Logic, Polynomials, Matrices & Complex Numbers

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(7) f(7) for the quadratic function f(x)=6x2−6x+10 f(x) = 6x^2 - 6x + 10 .
💡 Hint 1 of 3
Substitute x=7 x = 7 directly into f(x)=6x2−6x+10 f(x) = 6x^2 - 6x + 10 .
💡 Hint 2 of 3
Factor out 6x(x−1)+10=6(7)(6)+10 6x(x - 1) + 10 = 6(7)(6) + 10 .
💡 Hint 3 of 3
Compute 252+10 252 + 10 to obtain the final answer.
Substituting x=7 x = 7 gives f(7)=6(7)2−6(7)+10=294−42+10=262 f(7) = 6(7)^2 - 6(7) + 10 = 294 - 42 + 10 = 262 .
[Practice 2 · Easy] Find the positive root of the equation x2−13x+42=0 x^2 - 13x + 42 = 0 that is greater than 6 6 .
💡 Hint 1 of 3
Look for two integers whose sum is 13 13 and whose product is 42 42 .
💡 Hint 2 of 3
Factor the quadratic as (x−6)(x−7)=0 (x - 6)(x - 7) = 0 .
💡 Hint 3 of 3
Compare the two roots x=6 x = 6 and x=7 x = 7 and select the larger root.
Factoring gives (x−6)(x−7)=0 (x - 6)(x - 7) = 0 , so the roots are x=6 x = 6 and x=7 x = 7 . The root greater than 6 6 is x=7 x = 7 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+54=0 x^2 - 2kx + 54 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=54 a = 1, b = -2k, c = 54 into (−2k)2−4(1)(54)=0 (-2k)^2 - 4(1)(54) = 0 .
💡 Hint 3 of 3
Simplify 4k2=216 4k^2 = 216 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(54)=4k2−216=0  ⟹  k2=54 \Delta = (-2k)^2 - 4(1)(54) = 4k^2 - 216 = 0 \implies k^2 = 54 .
[Practice 4 · Hard] An arithmetic progression has first term a=6 a = 6 and common difference d=14 d = 14 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=6,d=14 n = 10, a = 6, d = 14 : S10=5[2(6)+9(14)] S_{10} = 5[2(6) + 9(14)] .
💡 Hint 3 of 3
Evaluate 5(12+126)=690 5(12 + 126) = 690 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(6)+9(14)]=5(138)=690 S_{10} = \frac{10}{2}[2(6) + 9(14)] = 5(138) = 690 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+6x2−7x+7 y = x^3 + 6x^2 - 7x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+6x2−7x+7 y = x^3 + 6x^2 - 7x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+12x−7 \frac{dy}{dx} = 3x^2 + 12x - 7 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+12(3)−7=56 3(3)^2 + 12(3) - 7 = 56 .
Differentiating gives dydx=3x2+12x−7 \frac{dy}{dx} = 3x^2 + 12x - 7 . At x=3 x = 3 , dydx=3(9)+36−7=56 \frac{dy}{dx} = 3(9) + 36 - 7 = 56 .
📝 Chapter Quiz
6

SAAT Functions, Sequences, Exponentials & Logarithms

🇸🇦 SAAT Module 6 — Functions, Series & Logs Core Mastery  ·  Horizontal/vertical asymptotes & removable holes  ·  Infinite geometric series S_∞ = a₁/(1 - r)  ·  Binomial expansion term T_{k+1}  ·  Logarithmic equations & change of base  ·  Even/odd symmetry & inverse functions

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for SAAT Functions, Sequences, Exponentials & Logarithms (SAAT Module 6 — Functions, Series & Logs).

● Definition 6.1 — Rational Asymptotes, Infinite Geometric Sums & Logarithm Laws

For a rational function f(x)=P(x)Q(x) f(x) = \frac{P(x)}{Q(x)} of degrees m m and n n : if \( m < n \), the horizontal asymptote is \( y = 0 \); if \( m = n \), it is \( y = \frac{\text{leading coeff of } P}{\text{leading coeff of } Q} \); common linear factors \( (x - c) \) create a point discontinuity (hole) at x=c x = c . An infinite geometric series converges if and only if \( |r| < 1 \), with sum \( S_\infty = \frac{a_1}{1 - r} \).

● Deep Conceptual Intuition — SAAT Functions, Sequences, Exponentials & Logarithms

Structural Invariants & Analytical Rigor: Every problem in SAAT Functions, Sequences, Exponentials & Logarithms reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

SAAT Functions, Sequences, Exponentials & Logarithms — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 2)² − 2, g(x) = x + 2; marked points Vertex (2, −2) (2, −2)Coordinate Curve & Structural Analysis-3-2-112345-2246xyVertex (2, −2)f(x) = (x − 2)² − 2g(x) = x + 2
Coordinate representation of f(x)=(x−2)2−2f(x) = (x - 2)^2 - 2 and secant line g(x)=x+2g(x) = x + 2 illustrating SAAT Functions, Sequences, Exponentials & Logarithms.
⊙ Explorer · Exponential Growth, Logarithmic Inverse & Geometric Convergence Lab
interactive
Value at x=2x = 26.756.75
Logarithm log⁡b(y/a1)\log_b(y/a_1)2.002.00
RegimeExponential Growth (b > 1)

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern SAAT Functions, Sequences, Exponentials & Logarithms.

Triangle ACB with sides 21, 28, 35; right angle at BACB212835
Orthogonal components and Euclidean distance relationship (21)2+(28)2=(35)2(21)^2 + (28)^2 = (35)^2 for SAAT Functions, Sequences, Exponentials & Logarithms.
Key Principle 6.1
Horizontal/vertical asymptotes & removable holes
Key Principle 6.2
Infinite geometric series S_∞ = a₁/(1 - r)
Key Principle 6.3
Binomial expansion term T_{k+1}
Key Principle 6.4
Logarithmic equations & change of base
◆ Why It Works — First-Principles Derivation (SAAT Functions, Sequences, Exponentials & Logarithms)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 6.A — Foundational Formulation (SAAT Functions, Sequences, Exponentials & Logarithms)

Problem: Given the quadratic function f(x)=x2−14x+57 f(x) = x^2 - 14x + 57 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −142=−7 -\frac{14}{2} = -7 .
2. Write (x−7)2=x2−14x+49 (x - 7)^2 = x^2 - 14x + 49 .
3. Adjust the constant term: f(x)=(x−7)2−49+57=(x−7)2+8 f(x) = (x - 7)^2 - 49 + 57 = (x - 7)^2 + 8 .
4. Since (x−7)2≥0 (x - 7)^2 \ge 0 for all real x x , the minimum value is k=8 k = 8 , achieved at x=7 x = 7 .

Final Answer: f(x)=(x−7)2+8 f(x) = (x - 7)^2 + 8 ; minimum value 8 8 at x=7 x = 7 .

Worked Example 6.B — Intermediate Multi-Step Synthesis (SAAT Functions, Sequences, Exponentials & Logarithms)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−14x+54 y = x^2 - 14x + 54 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−14x+54=2x+k  ⟹  x2−16x+(54−k)=0 x^2 - 14x + 54 = 2x + k \implies x^2 - 16x + (54 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−16)2−4(1)(54−k)>0 (-16)^2 - 4(1)(54 - k) > 0
256−216+4k>0  ⟹  4k>−40  ⟹  k>−10 256 - 216 + 4k > 0 \implies 4k > -40 \implies k > -10

Final Answer: k>−10 k > -10 .

Worked Example 6.C — Advanced Rate & Vector Application (SAAT Functions, Sequences, Exponentials & Logarithms)

Problem: Consider the cubic function g(x)=x3−21x2+147x+8 g(x) = x^3 - 21x^2 + 147x + 8 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=9 x = 9 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−42x+147=3(x−7)2 g'(x) = 3x^2 - 42x + 147 = 3(x - 7)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=7 x = 7 , with g(7)=8 g(7) = 8 . Thus (7,8) (7, 8) is the stationary point.
3. At x=9 x = 9 , the gradient is g′(9)=3(2)2=12 g'(9) = 3(2)^2 = 12 .

Final Answer: Stationary point (7,8) (7, 8) ; gradient at x=9 x = 9 is 12 12 .

Worked Example 6.D — Exam-Grade Challenge Synthesis (SAAT Functions, Sequences, Exponentials & Logarithms)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=7n2+8n S_n = 7n^2 + 8n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=7(1)2+8(1)=15 u_1 = S_1 = 7(1)^2 + 8(1) = 15 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[7n2+8n]−[7(n−1)2+8(n−1)]=14n+(1) u_n = \left[7n^2 + 8n\right] - \left[7(n-1)^2 + 8(n-1)\right] = 14n + (1)
3. The coefficient of n n gives the common difference d=14 d = 14 .
4. Substituting n=10 n = 10 yields u10=141 u_{10} = 141 .

Final Answer: un=14n+1 u_n = 14n + 1 , d=14 d = 14 , and u10=141 u_{10} = 141 .

⚠️ Common Exam Traps — SAAT Functions, Sequences, Exponentials & Logarithms

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (SAAT Functions, Sequences, Exponentials & Logarithms)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — SAAT Functions, Sequences, Exponentials & Logarithms

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(8) f(8) for the quadratic function f(x)=7x2−7x+10 f(x) = 7x^2 - 7x + 10 .
💡 Hint 1 of 3
Substitute x=8 x = 8 directly into f(x)=7x2−7x+10 f(x) = 7x^2 - 7x + 10 .
💡 Hint 2 of 3
Factor out 7x(x−1)+10=7(8)(7)+10 7x(x - 1) + 10 = 7(8)(7) + 10 .
💡 Hint 3 of 3
Compute 392+10 392 + 10 to obtain the final answer.
Substituting x=8 x = 8 gives f(8)=7(8)2−7(8)+10=448−56+10=402 f(8) = 7(8)^2 - 7(8) + 10 = 448 - 56 + 10 = 402 .
[Practice 2 · Easy] Find the positive root of the equation x2−15x+56=0 x^2 - 15x + 56 = 0 that is greater than 7 7 .
💡 Hint 1 of 3
Look for two integers whose sum is 15 15 and whose product is 56 56 .
💡 Hint 2 of 3
Factor the quadratic as (x−7)(x−8)=0 (x - 7)(x - 8) = 0 .
💡 Hint 3 of 3
Compare the two roots x=7 x = 7 and x=8 x = 8 and select the larger root.
Factoring gives (x−7)(x−8)=0 (x - 7)(x - 8) = 0 , so the roots are x=7 x = 7 and x=8 x = 8 . The root greater than 7 7 is x=8 x = 8 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+63=0 x^2 - 2kx + 63 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=63 a = 1, b = -2k, c = 63 into (−2k)2−4(1)(63)=0 (-2k)^2 - 4(1)(63) = 0 .
💡 Hint 3 of 3
Simplify 4k2=252 4k^2 = 252 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(63)=4k2−252=0  ⟹  k2=63 \Delta = (-2k)^2 - 4(1)(63) = 4k^2 - 252 = 0 \implies k^2 = 63 .
[Practice 4 · Hard] An arithmetic progression has first term a=7 a = 7 and common difference d=16 d = 16 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=7,d=16 n = 10, a = 7, d = 16 : S10=5[2(7)+9(16)] S_{10} = 5[2(7) + 9(16)] .
💡 Hint 3 of 3
Evaluate 5(14+144)=790 5(14 + 144) = 790 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(7)+9(16)]=5(158)=790 S_{10} = \frac{10}{2}[2(7) + 9(16)] = 5(158) = 790 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+7x2−8x+7 y = x^3 + 7x^2 - 8x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+7x2−8x+7 y = x^3 + 7x^2 - 8x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+14x−8 \frac{dy}{dx} = 3x^2 + 14x - 8 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+14(3)−8=61 3(3)^2 + 14(3) - 8 = 61 .
Differentiating gives dydx=3x2+14x−8 \frac{dy}{dx} = 3x^2 + 14x - 8 . At x=3 x = 3 , dydx=3(9)+42−8=61 \frac{dy}{dx} = 3(9) + 42 - 8 = 61 .
📝 Chapter Quiz
7

SAAT Trigonometry, Conic Sections & 3D Vectors

🇸🇦 SAAT Module 7 — Conics, Trig & 3D Vectors Core Mastery  ·  Compound & double-angle trig identities  ·  Parabola, ellipse & hyperbola foci & eccentricity  ·  3D vectors, dot product orthogonality & cross product  ·  Polar coordinates (r, θ) ↔ Cartesian (x, y)  ·  De Moivre's theorem for complex powers

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for SAAT Trigonometry, Conic Sections & 3D Vectors (SAAT Module 7 — Conics, Trig & 3D Vectors).

● Definition 7.1 — Conic Sections, Eccentricity & 3D Vector Orthogonality (SAAT Year 3)

In SAAT Year 3 Mathematics: (1) For an ellipse (x−h)2a2+(y−k)2b2=1 \frac{(x-h)^2}{a^2} + \frac{(y-k)^2}{b^2} = 1 (a>b a > b ), c2=a2−b2 c^2 = a^2 - b^2 and eccentricity e=ca∈(0,1) e = \frac{c}{a} \in (0, 1) ; for a hyperbola (x−h)2a2−(y−k)2b2=1 \frac{(x-h)^2}{a^2} - \frac{(y-k)^2}{b^2} = 1 , c2=a2+b2 c^2 = a^2 + b^2 , e=ca>1 e = \frac{c}{a} > 1 , and asymptotes have slopes ±ba \pm\frac{b}{a} (or ±ab \pm\frac{a}{b} if vertical); (2) Two non-zero vectors u,v \mathbf{u}, \mathbf{v} are orthogonal if and only if u⋅v=0 \mathbf{u} \cdot \mathbf{v} = 0 .

● Deep Conceptual Intuition — SAAT Trigonometry, Conic Sections & 3D Vectors

Structural Invariants & Analytical Rigor: Every problem in SAAT Trigonometry, Conic Sections & 3D Vectors reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

SAAT Trigonometry, Conic Sections & 3D Vectors — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 0)² − 2, g(x) = x + 1; marked points Vertex (0, −2) (0, −2)Coordinate Curve & Structural Analysis-3-2-112345246xyVertex (0, −2)f(x) = (x − 0)² − 2g(x) = x + 1
Coordinate representation of f(x)=(x−0)2−2f(x) = (x - 0)^2 - 2 and secant line g(x)=x+1g(x) = x + 1 illustrating SAAT Trigonometry, Conic Sections & 3D Vectors.
⊙ Explorer · Conic Sections (Ellipse / Hyperbola) Foci & Eccentricity Lab
interactive
Focal Distance c=∣a2−b2∣c = \sqrt{|a^2 - b^2|}c=2.65c = 2.65
Eccentricity e=c/ae = c/ae=0.66e = 0.66
Vertices(±4.00,0)(\pm 4.00, 0)

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern SAAT Trigonometry, Conic Sections & 3D Vectors.

Triangle ACB with sides 24, 32, 40; right angle at BACB243240
Orthogonal components and Euclidean distance relationship (24)2+(32)2=(40)2(24)^2 + (32)^2 = (40)^2 for SAAT Trigonometry, Conic Sections & 3D Vectors.
Key Principle 7.1
Compound & double-angle trig identities
Key Principle 7.2
Parabola, ellipse & hyperbola foci & eccentricity
Key Principle 7.3
3D vectors, dot product orthogonality & cross product
Key Principle 7.4
Polar coordinates (r, θ) ↔ Cartesian (x, y)
◆ Why It Works — First-Principles Derivation (SAAT Trigonometry, Conic Sections & 3D Vectors)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 7.A — Foundational Formulation (SAAT Trigonometry, Conic Sections & 3D Vectors)

Problem: Given the quadratic function f(x)=x2−16x+73 f(x) = x^2 - 16x + 73 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −162=−8 -\frac{16}{2} = -8 .
2. Write (x−8)2=x2−16x+64 (x - 8)^2 = x^2 - 16x + 64 .
3. Adjust the constant term: f(x)=(x−8)2−64+73=(x−8)2+9 f(x) = (x - 8)^2 - 64 + 73 = (x - 8)^2 + 9 .
4. Since (x−8)2≥0 (x - 8)^2 \ge 0 for all real x x , the minimum value is k=9 k = 9 , achieved at x=8 x = 8 .

Final Answer: f(x)=(x−8)2+9 f(x) = (x - 8)^2 + 9 ; minimum value 9 9 at x=8 x = 8 .

Worked Example 7.B — Intermediate Multi-Step Synthesis (SAAT Trigonometry, Conic Sections & 3D Vectors)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−16x+69 y = x^2 - 16x + 69 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−16x+69=2x+k  ⟹  x2−18x+(69−k)=0 x^2 - 16x + 69 = 2x + k \implies x^2 - 18x + (69 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−18)2−4(1)(69−k)>0 (-18)^2 - 4(1)(69 - k) > 0
324−276+4k>0  ⟹  4k>−48  ⟹  k>−12 324 - 276 + 4k > 0 \implies 4k > -48 \implies k > -12

Final Answer: k>−12 k > -12 .

Worked Example 7.C — Advanced Rate & Vector Application (SAAT Trigonometry, Conic Sections & 3D Vectors)

Problem: Consider the cubic function g(x)=x3−24x2+192x+9 g(x) = x^3 - 24x^2 + 192x + 9 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=10 x = 10 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−48x+192=3(x−8)2 g'(x) = 3x^2 - 48x + 192 = 3(x - 8)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=8 x = 8 , with g(8)=9 g(8) = 9 . Thus (8,9) (8, 9) is the stationary point.
3. At x=10 x = 10 , the gradient is g′(10)=3(2)2=12 g'(10) = 3(2)^2 = 12 .

Final Answer: Stationary point (8,9) (8, 9) ; gradient at x=10 x = 10 is 12 12 .

Worked Example 7.D — Exam-Grade Challenge Synthesis (SAAT Trigonometry, Conic Sections & 3D Vectors)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=8n2+9n S_n = 8n^2 + 9n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=8(1)2+9(1)=17 u_1 = S_1 = 8(1)^2 + 9(1) = 17 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[8n2+9n]−[8(n−1)2+9(n−1)]=16n+(1) u_n = \left[8n^2 + 9n\right] - \left[8(n-1)^2 + 9(n-1)\right] = 16n + (1)
3. The coefficient of n n gives the common difference d=16 d = 16 .
4. Substituting n=10 n = 10 yields u10=161 u_{10} = 161 .

Final Answer: un=16n+1 u_n = 16n + 1 , d=16 d = 16 , and u10=161 u_{10} = 161 .

⚠️ Common Exam Traps — SAAT Trigonometry, Conic Sections & 3D Vectors

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (SAAT Trigonometry, Conic Sections & 3D Vectors)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — SAAT Trigonometry, Conic Sections & 3D Vectors

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(9) f(9) for the quadratic function f(x)=8x2−8x+10 f(x) = 8x^2 - 8x + 10 .
💡 Hint 1 of 3
Substitute x=9 x = 9 directly into f(x)=8x2−8x+10 f(x) = 8x^2 - 8x + 10 .
💡 Hint 2 of 3
Factor out 8x(x−1)+10=8(9)(8)+10 8x(x - 1) + 10 = 8(9)(8) + 10 .
💡 Hint 3 of 3
Compute 576+10 576 + 10 to obtain the final answer.
Substituting x=9 x = 9 gives f(9)=8(9)2−8(9)+10=648−72+10=586 f(9) = 8(9)^2 - 8(9) + 10 = 648 - 72 + 10 = 586 .
[Practice 2 · Easy] Find the positive root of the equation x2−17x+72=0 x^2 - 17x + 72 = 0 that is greater than 8 8 .
💡 Hint 1 of 3
Look for two integers whose sum is 17 17 and whose product is 72 72 .
💡 Hint 2 of 3
Factor the quadratic as (x−8)(x−9)=0 (x - 8)(x - 9) = 0 .
💡 Hint 3 of 3
Compare the two roots x=8 x = 8 and x=9 x = 9 and select the larger root.
Factoring gives (x−8)(x−9)=0 (x - 8)(x - 9) = 0 , so the roots are x=8 x = 8 and x=9 x = 9 . The root greater than 8 8 is x=9 x = 9 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+72=0 x^2 - 2kx + 72 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=72 a = 1, b = -2k, c = 72 into (−2k)2−4(1)(72)=0 (-2k)^2 - 4(1)(72) = 0 .
💡 Hint 3 of 3
Simplify 4k2=288 4k^2 = 288 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(72)=4k2−288=0  ⟹  k2=72 \Delta = (-2k)^2 - 4(1)(72) = 4k^2 - 288 = 0 \implies k^2 = 72 .
[Practice 4 · Hard] An arithmetic progression has first term a=8 a = 8 and common difference d=18 d = 18 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=8,d=18 n = 10, a = 8, d = 18 : S10=5[2(8)+9(18)] S_{10} = 5[2(8) + 9(18)] .
💡 Hint 3 of 3
Evaluate 5(16+162)=890 5(16 + 162) = 890 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(8)+9(18)]=5(178)=890 S_{10} = \frac{10}{2}[2(8) + 9(18)] = 5(178) = 890 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+8x2−9x+7 y = x^3 + 8x^2 - 9x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+8x2−9x+7 y = x^3 + 8x^2 - 9x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+16x−9 \frac{dy}{dx} = 3x^2 + 16x - 9 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+16(3)−9=66 3(3)^2 + 16(3) - 9 = 66 .
Differentiating gives dydx=3x2+16x−9 \frac{dy}{dx} = 3x^2 + 16x - 9 . At x=3 x = 3 , dydx=3(9)+48−9=66 \frac{dy}{dx} = 3(9) + 48 - 9 = 66 .
📝 Chapter Quiz
8

SAAT Limits, Derivatives, Definite Integrals & Area

🇸🇦 SAAT Module 8 — Differential & Integral Calculus Core Mastery  ·  Algebraic limits & limits at infinity  ·  Power, product & quotient derivative rules  ·  Critical points, local extrema & tangent lines  ·  Antiderivatives & Fundamental Theorem of Calculus  ·  Area under a curve & kinematic velocity/acceleration

Mastering the essential concepts, analytical methods, and exam-grade problem-solving techniques for SAAT Limits, Derivatives, Definite Integrals & Area (SAAT Module 8 — Differential & Integral Calculus).

● Definition 8.1 — High-Speed SAAT Calculus Rules (Limits, Extrema & FTC)

High-yield SAAT Year 3 Calculus shortcuts: (1) 0/0 Algebraic Limits: factor and cancel (x−a) (x - a) , or differentiate numerator and denominator: lim⁡x→axn−anx−a=nan−1 \lim_{x\to a}\frac{x^n - a^n}{x - a} = na^{n-1} ; (2) Critical Points: local maxima and minima of a polynomial f(x) f(x) occur where f′(x)=0 f'(x) = 0 ; (3) Fundamental Theorem of Calculus: if F′(x)=f(x) F'(x) = f(x) , then ∫abf(x) dx=F(b)−F(a) \int_a^b f(x)\,dx = F(b) - F(a) , and ∫−aag(x) dx=0 \int_{-a}^{a} g(x)\,dx = 0 for any odd function g(−x)=−g(x) g(-x) = -g(x) .

● Deep Conceptual Intuition — SAAT Limits, Derivatives, Definite Integrals & Area

Structural Invariants & Analytical Rigor: Every problem in SAAT Limits, Derivatives, Definite Integrals & Area reduces to identifying the underlying algebraic or geometric structure before computing. Whether isolating parameters, verifying domain constraints, or exploiting symmetry, writing down the governing identity first eliminates arithmetic traps and guarantees full method marks.

SAAT Limits, Derivatives, Definite Integrals & Area — Coordinate Curve & Structural Analysis — Coordinate plane with graph of f(x) = (x − 1)² − 2, g(x) = x + 2; marked points Vertex (1, −2) (1, −2)Coordinate Curve & Structural Analysis-3-2-112345-2246xyVertex (1, −2)f(x) = (x − 1)² − 2g(x) = x + 2
Coordinate representation of f(x)=(x−1)2−2f(x) = (x - 1)^2 - 2 and secant line g(x)=x+2g(x) = x + 2 illustrating SAAT Limits, Derivatives, Definite Integrals & Area.
⊙ Explorer · Fundamental Theorem of Calculus: Derivative, Curve & Area Lab
interactive
Accumulated Area ∫0bf(x) dx\int_0^b f(x)\,dx2.672.67
Instantaneous Rate f′(b)f'(b)4.004.00
Function Value f(b)f(b)4.004.00

Drag the sliders or directly manipulate the canvas to explore how changes in the parameters govern SAAT Limits, Derivatives, Definite Integrals & Area.

Triangle ACB with sides 27, 36, 45; right angle at BACB273645
Orthogonal components and Euclidean distance relationship (27)2+(36)2=(45)2(27)^2 + (36)^2 = (45)^2 for SAAT Limits, Derivatives, Definite Integrals & Area.
Key Principle 8.1
Algebraic limits & limits at infinity
Key Principle 8.2
Power, product & quotient derivative rules
Key Principle 8.3
Critical points, local extrema & tangent lines
Key Principle 8.4
Antiderivatives & Fundamental Theorem of Calculus
◆ Why It Works — First-Principles Derivation (SAAT Limits, Derivatives, Definite Integrals & Area)

First-Principles Justification: Any quadratic or bilinear relation ax2+bx+c=0 ax^2 + bx + c = 0 can be transformed by completing the square:

a ⁣(x+b2a)2=b2−4ac4a. a\!\left(x + \frac{b}{2a}\right)^2 = \frac{b^2 - 4ac}{4a}.

This single identity simultaneously proves the quadratic formula, determines the exact turning-point coordinates (−b2a,c−b24a) \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right) , and establishes the discriminant criterion Δ=b2−4ac \Delta = b^2 - 4ac for tangency and root existence.

Worked Example 8.A — Foundational Formulation (SAAT Limits, Derivatives, Definite Integrals & Area)

Problem: Given the quadratic function f(x)=x2−18x+91 f(x) = x^2 - 18x + 91 , express f(x) f(x) in the completed-square form (x−h)2+k (x - h)^2 + k and state its minimum value and the value of x x at which it occurs.

Step-by-Step Solution:
1. Halve the coefficient of x x : −182=−9 -\frac{18}{2} = -9 .
2. Write (x−9)2=x2−18x+81 (x - 9)^2 = x^2 - 18x + 81 .
3. Adjust the constant term: f(x)=(x−9)2−81+91=(x−9)2+10 f(x) = (x - 9)^2 - 81 + 91 = (x - 9)^2 + 10 .
4. Since (x−9)2≥0 (x - 9)^2 \ge 0 for all real x x , the minimum value is k=10 k = 10 , achieved at x=9 x = 9 .

Final Answer: f(x)=(x−9)2+10 f(x) = (x - 9)^2 + 10 ; minimum value 10 10 at x=9 x = 9 .

Worked Example 8.B — Intermediate Multi-Step Synthesis (SAAT Limits, Derivatives, Definite Integrals & Area)

Problem: The line y=2x+k y = 2x + k intersects the curve y=x2−18x+86 y = x^2 - 18x + 86 at two distinct points. Find the range of possible values for the constant k k .

Step-by-Step Solution:
1. Equate the line and curve equations:
x2−18x+86=2x+k  ⟹  x2−20x+(86−k)=0 x^2 - 18x + 86 = 2x + k \implies x^2 - 20x + (86 - k) = 0
2. For two distinct real intersections, the discriminant must satisfy Δ=b2−4ac>0 \Delta = b^2 - 4ac > 0 :
(−20)2−4(1)(86−k)>0 (-20)^2 - 4(1)(86 - k) > 0
400−344+4k>0  ⟹  4k>−56  ⟹  k>−14 400 - 344 + 4k > 0 \implies 4k > -56 \implies k > -14

Final Answer: k>−14 k > -14 .

Worked Example 8.C — Advanced Rate & Vector Application (SAAT Limits, Derivatives, Definite Integrals & Area)

Problem: Consider the cubic function g(x)=x3−27x2+243x+10 g(x) = x^3 - 27x^2 + 243x + 10 . Find the coordinates of the stationary point of inflection and the gradient of the curve at x=11 x = 11 .

Step-by-Step Solution:
1. Differentiate term by term:
g′(x)=3x2−54x+243=3(x−9)2 g'(x) = 3x^2 - 54x + 243 = 3(x - 9)^2
2. Setting g′(x)=0 g'(x) = 0 yields x=9 x = 9 , with g(9)=10 g(9) = 10 . Thus (9,10) (9, 10) is the stationary point.
3. At x=11 x = 11 , the gradient is g′(11)=3(2)2=12 g'(11) = 3(2)^2 = 12 .

Final Answer: Stationary point (9,10) (9, 10) ; gradient at x=11 x = 11 is 12 12 .

Worked Example 8.D — Exam-Grade Challenge Synthesis (SAAT Limits, Derivatives, Definite Integrals & Area)

Problem: Let Sn S_n denote the sum of the first n n terms of an arithmetic progression where Sn=9n2+10n S_n = 9n^2 + 10n . Find an expression for the n n -th term un u_n , determine the common difference d d , and evaluate u10 u_{10} .

Step-by-Step Solution:
1. For n=1 n = 1 , u1=S1=9(1)2+10(1)=19 u_1 = S_1 = 9(1)^2 + 10(1) = 19 .
2. For n≥2 n \ge 2 , use the fundamental identity un=Sn−Sn−1 u_n = S_n - S_{n-1} :
un=[9n2+10n]−[9(n−1)2+10(n−1)]=18n+(1) u_n = \left[9n^2 + 10n\right] - \left[9(n-1)^2 + 10(n-1)\right] = 18n + (1)
3. The coefficient of n n gives the common difference d=18 d = 18 .
4. Substituting n=10 n = 10 yields u10=181 u_{10} = 181 .

Final Answer: un=18n+1 u_n = 18n + 1 , d=18 d = 18 , and u10=181 u_{10} = 181 .

⚠️ Common Exam Traps — SAAT Limits, Derivatives, Definite Integrals & Area

1. Sign & Domain Omissions: Always verify whether negative roots or boundary values violate denominator, square-root, or logarithmic domain restrictions before writing your final answer.

2. Premature Rounding: Keep exact fractions, surds, or π\pi expressions throughout intermediate steps and round only at the final line if requested.

Error Diagnosis — Common Student Traps vs. Exam-Board Method (SAAT Limits, Derivatives, Definite Integrals & Area)
Common Student Trap Why It Fails Mathematically Correct Exam-Board Method
Canceling terms across a sum in x2+ax+a \frac{x^2 + a}{x + a} Division only cancels common multiplicative factors of the entire numerator and denominator. Factorize numerator and denominator completely before canceling common binomial factors.
Writing (a+b)2=a2+b2 (a + b)^2 = a^2 + b^2 when squaring binomials Omits the cross-product term 2ab 2ab required by the distributive law. Always expand as (a±b)2=a2±2ab+b2 (a \pm b)^2 = a^2 \pm 2ab + b^2 .
Solving quadratic inequalities by treating \( < \) like \( = \) without a sign chart A parabola changes sign at its distinct real roots, so the solution is an interval or union of rays. Find the critical roots first, then sketch the parabola or test a point in each interval.
▲ Exam Pacing & Verification Strategy — SAAT Limits, Derivatives, Definite Integrals & Area

10-Second Sanity Check: Substitute a simple test value (such as x=0,1, x = 0, 1, or 2 2 ) into both your simplified expression and the original problem statement. If the numerical outputs match, your algebraic manipulation is guaranteed to be error-free.

[Practice 1 · Easy] Evaluate f(10) f(10) for the quadratic function f(x)=9x2−9x+10 f(x) = 9x^2 - 9x + 10 .
💡 Hint 1 of 3
Substitute x=10 x = 10 directly into f(x)=9x2−9x+10 f(x) = 9x^2 - 9x + 10 .
💡 Hint 2 of 3
Factor out 9x(x−1)+10=9(10)(9)+10 9x(x - 1) + 10 = 9(10)(9) + 10 .
💡 Hint 3 of 3
Compute 810+10 810 + 10 to obtain the final answer.
Substituting x=10 x = 10 gives f(10)=9(10)2−9(10)+10=900−90+10=820 f(10) = 9(10)^2 - 9(10) + 10 = 900 - 90 + 10 = 820 .
[Practice 2 · Easy] Find the positive root of the equation x2−19x+90=0 x^2 - 19x + 90 = 0 that is greater than 9 9 .
💡 Hint 1 of 3
Look for two integers whose sum is 19 19 and whose product is 90 90 .
💡 Hint 2 of 3
Factor the quadratic as (x−9)(x−10)=0 (x - 9)(x - 10) = 0 .
💡 Hint 3 of 3
Compare the two roots x=9 x = 9 and x=10 x = 10 and select the larger root.
Factoring gives (x−9)(x−10)=0 (x - 9)(x - 10) = 0 , so the roots are x=9 x = 9 and x=10 x = 10 . The root greater than 9 9 is x=10 x = 10 .
[Practice 3 · Medium] If the quadratic equation x2−2kx+81=0 x^2 - 2kx + 81 = 0 has equal (repeated) real roots and k>0 k > 0 , find the exact value of k2 k^2 .
💡 Hint 1 of 3
For equal real roots, the discriminant Δ=b2−4ac \Delta = b^2 - 4ac must equal zero.
💡 Hint 2 of 3
Substitute a=1,b=−2k,c=81 a = 1, b = -2k, c = 81 into (−2k)2−4(1)(81)=0 (-2k)^2 - 4(1)(81) = 0 .
💡 Hint 3 of 3
Simplify 4k2=324 4k^2 = 324 and divide both sides by 4.
Setting the discriminant to zero: Δ=(−2k)2−4(1)(81)=4k2−324=0  ⟹  k2=81 \Delta = (-2k)^2 - 4(1)(81) = 4k^2 - 324 = 0 \implies k^2 = 81 .
[Practice 4 · Hard] An arithmetic progression has first term a=9 a = 9 and common difference d=20 d = 20 . Find the sum of the first 10 10 terms, S10 S_{10} .
💡 Hint 1 of 3
Recall the arithmetic series sum formula Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] .
💡 Hint 2 of 3
Substitute n=10,a=9,d=20 n = 10, a = 9, d = 20 : S10=5[2(9)+9(20)] S_{10} = 5[2(9) + 9(20)] .
💡 Hint 3 of 3
Evaluate 5(18+180)=990 5(18 + 180) = 990 .
Using Sn=n2[2a+(n−1)d] S_n = \frac{n}{2}[2a + (n - 1)d] , we have S10=102[2(9)+9(20)]=5(198)=990 S_{10} = \frac{10}{2}[2(9) + 9(20)] = 5(198) = 990 .
[Practice 5 · Hard] Find the instantaneous rate of change dydx \frac{dy}{dx} of the curve y=x3+9x2−10x+7 y = x^3 + 9x^2 - 10x + 7 at x=3 x = 3 .
💡 Hint 1 of 3
Differentiate y=x3+9x2−10x+7 y = x^3 + 9x^2 - 10x + 7 term by term with respect to x x .
💡 Hint 2 of 3
The derivative is dydx=3x2+18x−10 \frac{dy}{dx} = 3x^2 + 18x - 10 .
💡 Hint 3 of 3
Substitute x=3 x = 3 : 3(3)2+18(3)−10=71 3(3)^2 + 18(3) - 10 = 71 .
Differentiating gives dydx=3x2+18x−10 \frac{dy}{dx} = 3x^2 + 18x - 10 . At x=3 x = 3 , dydx=3(9)+54−10=71 \frac{dy}{dx} = 3(9) + 54 - 10 = 71 .
📝 Chapter Quiz
§

Practice set

Fifty graded English GAT & SAAT (Qiyas) problems spanning all eight core chapters. Click any problem for the complete step-by-step worked solution.

1

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] Find the equation of the tangent line to the curve y=x3−3x2+6x+2 y = x^3 - 3x^2 + 6x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Basic
Curve & Tangent Line at x = 2 (Problem 1) — Coordinate plane with graph of y = f(x); marked points P(2, 10) (2, 10)Curve & Tangent Line at x = 2 (Problem 1)12351015xyP(2, 10)y = f(x)

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−3(2)2+6(2)+2=8−12+12+2=10. y(2) = 2^3 - 3(2)^2 + 6(2) + 2 = 8 - 12 + 12 + 2 = 10.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−6x+6. \frac{dy}{dx} = 3x^2 - 6x + 6.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−6(2)+6=6 m = 3(4) - 6(2) + 6 = 6 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(10)=6(x−2)  ⟹  y=6x+(−2). y - (10) = 6(x - 2) \implies y = 6x + (-2).
Final Answer: y=6x+(−2) y = 6x + (-2) , crossing the y y -axis at (0,−2) (0, -2) .

2

[GAT Ratios, Percentages, Speed & Work-Rate Models] An arithmetic sequence has first term u1=4 u_1 = 4 and common difference d=9 d = 9 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Basic

Step 1 (General Term Formula): For an arithmetic progression with first term u1=4 u_1 = 4 and common difference d=9 d = 9 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=4+11(9)=4+99=103. u_{12} = 4 + 11(9) = 4 + 99 = 103.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(4+103)=6(107)=642. S_{12} = \frac{12}{2}(4 + 103) = 6(107) = 642.
Final Answer: u12=103 u_{12} = 103 and S12=642 S_{12} = 642 .

3

[GAT Quantitative Comparisons & Shaded Geometry] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=15 cm BC = 15\text{ cm} and AC=20 cm AC = 20\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Basic
Triangle ACB with sides 20, 15, 25; right angle at BACB201525

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(15)2+(20)2=225+400=625=25 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(15)^2 + (20)^2} = \sqrt{225 + 400} = \sqrt{625} = 25\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(15)(20)=150 cm2 [ABC] = \frac{1}{2}(15)(20) = 150\text{ cm}^2 , and the semiperimeter is s=15+20+252=30 cm s = \frac{15 + 20 + 25}{2} = 30\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=15030=5 cm. r = \frac{[ABC]}{s} = \frac{150}{30} = 5\text{ cm}.
Final Answer: AB=25 cm,  Area=150 cm2,  r=5 cm AB = 25\text{ cm},\; \text{Area} = 150\text{ cm}^2,\; r = 5\text{ cm} .

4

[GAT & SAAT Data Interpretation, Counting & Probability] The function f(x)=6x+7x−6 f(x) = \frac{6x + 7}{x - 6} is defined for x≠6 x \ne 6 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=7 f(x) = 7 .

Basic

Step 1 (Algebraic Inversion): Set y=6x+7x−6 y = \frac{6x + 7}{x - 6} and multiply both sides by (x−6) (x - 6) :
y(x−6)=6x+7  ⟹  xy−6y=6x+7  ⟹  x(y−6)=6y+7. y(x - 6) = 6x + 7 \implies xy - 6y = 6x + 7 \implies x(y - 6) = 6y + 7.

Step 2 (Domain of Inverse): Dividing by (y−6) (y - 6) and swapping x x and y y gives:
f−1(x)=6x+7x−6,with domain x∈R,  x≠6. f^{-1}(x) = \frac{6x + 7}{x - 6}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 6.

Step 3 (Solving f(x)=7 f(x) = 7 ): Since f f is self-inverse, x=f−1(7)=6(7)+7(7)−6=49 x = f^{-1}(7) = \frac{6(7) + 7}{(7) - 6} = 49 .
Final Answer: f−1(x)=6x+7x−6  (x≠6) f^{-1}(x) = \frac{6x + 7}{x - 6} \; (x \ne 6) , and x=49 x = 49 .

5

[SAAT Logic, Polynomials, Matrices & Complex Numbers] Solve the logarithmic equation log⁡2(x−7)+log⁡2(x+7)=log⁡2(147) \log_2(x - 7) + \log_2(x + 7) = \log_2(147) for x>7 x > 7 , showing why the negative root must be rejected.

Basic
Quadratic Intersection x² − 49 = 147 (Problem 5) — Coordinate plane with graph of y = x² − 49; marked points Valid x = 14 (14, 147)Quadratic Intersection x² − 49 = 147 (Problem 5)-15-10-55101550100150xyValid x = 14y = x² − 49

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>7 x > 7 :
log⁡2((x−7)(x+7))=log⁡2(147)  ⟹  x2−49=147. \log_2\big((x - 7)(x + 7)\big) = \log_2(147) \implies x^2 - 49 = 147.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=196  ⟹  x=±14 x^2 = 196 \implies x = \pm 14 . Since log⁡2(x−7) \log_2(x - 7) requires x−7>0  ⟺  x>7 x - 7 > 0 \iff x > 7 , the negative root x=−14 x = -14 is extraneous and must be rejected.
Final Answer: x=14 x = 14 .

6

[SAAT Functions, Sequences, Exponentials & Logarithms] Find the equation of the tangent line to the curve y=x3−8x2+5x+2 y = x^3 - 8x^2 + 5x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Basic

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−8(2)2+5(2)+2=8−32+10+2=−12. y(2) = 2^3 - 8(2)^2 + 5(2) + 2 = 8 - 32 + 10 + 2 = -12.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−16x+5. \frac{dy}{dx} = 3x^2 - 16x + 5.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−16(2)+5=−15 m = 3(4) - 16(2) + 5 = -15 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(−12)=−15(x−2)  ⟹  y=−15x+(18). y - (-12) = -15(x - 2) \implies y = -15x + (18).
Final Answer: y=−15x+(18) y = -15x + (18) , crossing the y y -axis at (0,18) (0, 18) .

7

[SAAT Trigonometry, Conic Sections & 3D Vectors] An arithmetic sequence has first term u1=2 u_1 = 2 and common difference d=8 d = 8 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Basic

Step 1 (General Term Formula): For an arithmetic progression with first term u1=2 u_1 = 2 and common difference d=8 d = 8 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=2+11(8)=2+88=90. u_{12} = 2 + 11(8) = 2 + 88 = 90.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(2+90)=6(92)=552. S_{12} = \frac{12}{2}(2 + 90) = 6(92) = 552.
Final Answer: u12=90 u_{12} = 90 and S12=552 S_{12} = 552 .

8

[SAAT Limits, Derivatives, Definite Integrals & Area] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=9 cm BC = 9\text{ cm} and AC=12 cm AC = 12\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Basic

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(9)2+(12)2=81+144=225=15 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(9)^2 + (12)^2} = \sqrt{81 + 144} = \sqrt{225} = 15\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(9)(12)=54 cm2 [ABC] = \frac{1}{2}(9)(12) = 54\text{ cm}^2 , and the semiperimeter is s=9+12+152=18 cm s = \frac{9 + 12 + 15}{2} = 18\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=5418=3 cm. r = \frac{[ABC]}{s} = \frac{54}{18} = 3\text{ cm}.
Final Answer: AB=15 cm,  Area=54 cm2,  r=3 cm AB = 15\text{ cm},\; \text{Area} = 54\text{ cm}^2,\; r = 3\text{ cm} .

9

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] The function f(x)=4x+6x−4 f(x) = \frac{4x + 6}{x - 4} is defined for x≠4 x \ne 4 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=5 f(x) = 5 .

Basic

Step 1 (Algebraic Inversion): Set y=4x+6x−4 y = \frac{4x + 6}{x - 4} and multiply both sides by (x−4) (x - 4) :
y(x−4)=4x+6  ⟹  xy−4y=4x+6  ⟹  x(y−4)=4y+6. y(x - 4) = 4x + 6 \implies xy - 4y = 4x + 6 \implies x(y - 4) = 4y + 6.

Step 2 (Domain of Inverse): Dividing by (y−4) (y - 4) and swapping x x and y y gives:
f−1(x)=4x+6x−4,with domain x∈R,  x≠4. f^{-1}(x) = \frac{4x + 6}{x - 4}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 4.

Step 3 (Solving f(x)=5 f(x) = 5 ): Since f f is self-inverse, x=f−1(5)=4(5)+6(5)−4=26 x = f^{-1}(5) = \frac{4(5) + 6}{(5) - 4} = 26 .
Final Answer: f−1(x)=4x+6x−4  (x≠4) f^{-1}(x) = \frac{4x + 6}{x - 4} \; (x \ne 4) , and x=26 x = 26 .

10

[GAT Ratios, Percentages, Speed & Work-Rate Models] Solve the logarithmic equation log⁡2(x−5)+log⁡2(x+5)=log⁡2(75) \log_2(x - 5) + \log_2(x + 5) = \log_2(75) for x>5 x > 5 , showing why the negative root must be rejected.

Basic

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>5 x > 5 :
log⁡2((x−5)(x+5))=log⁡2(75)  ⟹  x2−25=75. \log_2\big((x - 5)(x + 5)\big) = \log_2(75) \implies x^2 - 25 = 75.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=100  ⟹  x=±10 x^2 = 100 \implies x = \pm 10 . Since log⁡2(x−5) \log_2(x - 5) requires x−5>0  ⟺  x>5 x - 5 > 0 \iff x > 5 , the negative root x=−10 x = -10 is extraneous and must be rejected.
Final Answer: x=10 x = 10 .

11

[GAT Quantitative Comparisons & Shaded Geometry] Find the equation of the tangent line to the curve y=x3−6x2+4x+2 y = x^3 - 6x^2 + 4x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Basic
Curve & Tangent Line at x = 2 (Problem 11) — Coordinate plane with graph of y = f(x); marked points P(2, −6) (2, −6)Curve & Tangent Line at x = 2 (Problem 11)123-10-5510xyP(2, −6)y = f(x)

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−6(2)2+4(2)+2=8−24+8+2=−6. y(2) = 2^3 - 6(2)^2 + 4(2) + 2 = 8 - 24 + 8 + 2 = -6.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−12x+4. \frac{dy}{dx} = 3x^2 - 12x + 4.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−12(2)+4=−8 m = 3(4) - 12(2) + 4 = -8 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(−6)=−8(x−2)  ⟹  y=−8x+(10). y - (-6) = -8(x - 2) \implies y = -8x + (10).
Final Answer: y=−8x+(10) y = -8x + (10) , crossing the y y -axis at (0,10) (0, 10) .

12

[GAT & SAAT Data Interpretation, Counting & Probability] An arithmetic sequence has first term u1=7 u_1 = 7 and common difference d=7 d = 7 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Basic

Step 1 (General Term Formula): For an arithmetic progression with first term u1=7 u_1 = 7 and common difference d=7 d = 7 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=7+11(7)=7+77=84. u_{12} = 7 + 11(7) = 7 + 77 = 84.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(7+84)=6(91)=546. S_{12} = \frac{12}{2}(7 + 84) = 6(91) = 546.
Final Answer: u12=84 u_{12} = 84 and S12=546 S_{12} = 546 .

13

[SAAT Logic, Polynomials, Matrices & Complex Numbers] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=24 cm BC = 24\text{ cm} and AC=32 cm AC = 32\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Basic
Triangle ACB with sides 32, 24, 40; right angle at BACB322440

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(24)2+(32)2=576+1024=1600=40 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(24)^2 + (32)^2} = \sqrt{576 + 1024} = \sqrt{1600} = 40\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(24)(32)=384 cm2 [ABC] = \frac{1}{2}(24)(32) = 384\text{ cm}^2 , and the semiperimeter is s=24+32+402=48 cm s = \frac{24 + 32 + 40}{2} = 48\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=38448=8 cm. r = \frac{[ABC]}{s} = \frac{384}{48} = 8\text{ cm}.
Final Answer: AB=40 cm,  Area=384 cm2,  r=8 cm AB = 40\text{ cm},\; \text{Area} = 384\text{ cm}^2,\; r = 8\text{ cm} .

14

[SAAT Functions, Sequences, Exponentials & Logarithms] The function f(x)=2x+5x−2 f(x) = \frac{2x + 5}{x - 2} is defined for x≠2 x \ne 2 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=3 f(x) = 3 .

Basic

Step 1 (Algebraic Inversion): Set y=2x+5x−2 y = \frac{2x + 5}{x - 2} and multiply both sides by (x−2) (x - 2) :
y(x−2)=2x+5  ⟹  xy−2y=2x+5  ⟹  x(y−2)=2y+5. y(x - 2) = 2x + 5 \implies xy - 2y = 2x + 5 \implies x(y - 2) = 2y + 5.

Step 2 (Domain of Inverse): Dividing by (y−2) (y - 2) and swapping x x and y y gives:
f−1(x)=2x+5x−2,with domain x∈R,  x≠2. f^{-1}(x) = \frac{2x + 5}{x - 2}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 2.

Step 3 (Solving f(x)=3 f(x) = 3 ): Since f f is self-inverse, x=f−1(3)=2(3)+5(3)−2=11 x = f^{-1}(3) = \frac{2(3) + 5}{(3) - 2} = 11 .
Final Answer: f−1(x)=2x+5x−2  (x≠2) f^{-1}(x) = \frac{2x + 5}{x - 2} \; (x \ne 2) , and x=11 x = 11 .

15

[SAAT Trigonometry, Conic Sections & 3D Vectors] Solve the logarithmic equation log⁡2(x−3)+log⁡2(x+3)=log⁡2(27) \log_2(x - 3) + \log_2(x + 3) = \log_2(27) for x>3 x > 3 , showing why the negative root must be rejected.

Basic
Quadratic Intersection x² − 9 = 27 (Problem 15) — Coordinate plane with graph of y = x² − 9; marked points Valid x = 6 (6, 27)Quadratic Intersection x² − 9 = 27 (Problem 15)-6-4-2246-10102030xyValid x = 6y = x² − 9

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>3 x > 3 :
log⁡2((x−3)(x+3))=log⁡2(27)  ⟹  x2−9=27. \log_2\big((x - 3)(x + 3)\big) = \log_2(27) \implies x^2 - 9 = 27.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=36  ⟹  x=±6 x^2 = 36 \implies x = \pm 6 . Since log⁡2(x−3) \log_2(x - 3) requires x−3>0  ⟺  x>3 x - 3 > 0 \iff x > 3 , the negative root x=−6 x = -6 is extraneous and must be rejected.
Final Answer: x=6 x = 6 .

16

[SAAT Limits, Derivatives, Definite Integrals & Area] Find the equation of the tangent line to the curve y=x3−4x2+3x+2 y = x^3 - 4x^2 + 3x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Basic

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−4(2)2+3(2)+2=8−16+6+2=0. y(2) = 2^3 - 4(2)^2 + 3(2) + 2 = 8 - 16 + 6 + 2 = 0.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−8x+3. \frac{dy}{dx} = 3x^2 - 8x + 3.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−8(2)+3=−1 m = 3(4) - 8(2) + 3 = -1 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(0)=−1(x−2)  ⟹  y=−1x+(2). y - (0) = -1(x - 2) \implies y = -1x + (2).
Final Answer: y=−1x+(2) y = -1x + (2) , crossing the y y -axis at (0,2) (0, 2) .

17

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] An arithmetic sequence has first term u1=5 u_1 = 5 and common difference d=6 d = 6 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Intermediate

Step 1 (General Term Formula): For an arithmetic progression with first term u1=5 u_1 = 5 and common difference d=6 d = 6 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=5+11(6)=5+66=71. u_{12} = 5 + 11(6) = 5 + 66 = 71.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(5+71)=6(76)=456. S_{12} = \frac{12}{2}(5 + 71) = 6(76) = 456.
Final Answer: u12=71 u_{12} = 71 and S12=456 S_{12} = 456 .

18

[GAT Ratios, Percentages, Speed & Work-Rate Models] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=18 cm BC = 18\text{ cm} and AC=24 cm AC = 24\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Intermediate

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(18)2+(24)2=324+576=900=30 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(18)^2 + (24)^2} = \sqrt{324 + 576} = \sqrt{900} = 30\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(18)(24)=216 cm2 [ABC] = \frac{1}{2}(18)(24) = 216\text{ cm}^2 , and the semiperimeter is s=18+24+302=36 cm s = \frac{18 + 24 + 30}{2} = 36\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=21636=6 cm. r = \frac{[ABC]}{s} = \frac{216}{36} = 6\text{ cm}.
Final Answer: AB=30 cm,  Area=216 cm2,  r=6 cm AB = 30\text{ cm},\; \text{Area} = 216\text{ cm}^2,\; r = 6\text{ cm} .

19

[GAT Quantitative Comparisons & Shaded Geometry] The function f(x)=7x+4x−7 f(x) = \frac{7x + 4}{x - 7} is defined for x≠7 x \ne 7 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=8 f(x) = 8 .

Intermediate

Step 1 (Algebraic Inversion): Set y=7x+4x−7 y = \frac{7x + 4}{x - 7} and multiply both sides by (x−7) (x - 7) :
y(x−7)=7x+4  ⟹  xy−7y=7x+4  ⟹  x(y−7)=7y+4. y(x - 7) = 7x + 4 \implies xy - 7y = 7x + 4 \implies x(y - 7) = 7y + 4.

Step 2 (Domain of Inverse): Dividing by (y−7) (y - 7) and swapping x x and y y gives:
f−1(x)=7x+4x−7,with domain x∈R,  x≠7. f^{-1}(x) = \frac{7x + 4}{x - 7}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 7.

Step 3 (Solving f(x)=8 f(x) = 8 ): Since f f is self-inverse, x=f−1(8)=7(8)+4(8)−7=60 x = f^{-1}(8) = \frac{7(8) + 4}{(8) - 7} = 60 .
Final Answer: f−1(x)=7x+4x−7  (x≠7) f^{-1}(x) = \frac{7x + 4}{x - 7} \; (x \ne 7) , and x=60 x = 60 .

20

[GAT & SAAT Data Interpretation, Counting & Probability] Solve the logarithmic equation log⁡2(x−8)+log⁡2(x+8)=log⁡2(192) \log_2(x - 8) + \log_2(x + 8) = \log_2(192) for x>8 x > 8 , showing why the negative root must be rejected.

Intermediate

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>8 x > 8 :
log⁡2((x−8)(x+8))=log⁡2(192)  ⟹  x2−64=192. \log_2\big((x - 8)(x + 8)\big) = \log_2(192) \implies x^2 - 64 = 192.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=256  ⟹  x=±16 x^2 = 256 \implies x = \pm 16 . Since log⁡2(x−8) \log_2(x - 8) requires x−8>0  ⟺  x>8 x - 8 > 0 \iff x > 8 , the negative root x=−16 x = -16 is extraneous and must be rejected.
Final Answer: x=16 x = 16 .

21

[SAAT Logic, Polynomials, Matrices & Complex Numbers] Find the equation of the tangent line to the curve y=x3−2x2+10x+2 y = x^3 - 2x^2 + 10x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Intermediate
Curve & Tangent Line at x = 2 (Problem 21) — Coordinate plane with graph of y = f(x); marked points P(2, 22) (2, 22)Curve & Tangent Line at x = 2 (Problem 21)1231020xyP(2, 22)y = f(x)

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−2(2)2+10(2)+2=8−8+20+2=22. y(2) = 2^3 - 2(2)^2 + 10(2) + 2 = 8 - 8 + 20 + 2 = 22.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−4x+10. \frac{dy}{dx} = 3x^2 - 4x + 10.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−4(2)+10=14 m = 3(4) - 4(2) + 10 = 14 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(22)=14(x−2)  ⟹  y=14x+(−6). y - (22) = 14(x - 2) \implies y = 14x + (-6).
Final Answer: y=14x+(−6) y = 14x + (-6) , crossing the y y -axis at (0,−6) (0, -6) .

22

[SAAT Functions, Sequences, Exponentials & Logarithms] An arithmetic sequence has first term u1=3 u_1 = 3 and common difference d=5 d = 5 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Intermediate

Step 1 (General Term Formula): For an arithmetic progression with first term u1=3 u_1 = 3 and common difference d=5 d = 5 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=3+11(5)=3+55=58. u_{12} = 3 + 11(5) = 3 + 55 = 58.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(3+58)=6(61)=366. S_{12} = \frac{12}{2}(3 + 58) = 6(61) = 366.
Final Answer: u12=58 u_{12} = 58 and S12=366 S_{12} = 366 .

23

[SAAT Trigonometry, Conic Sections & 3D Vectors] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=12 cm BC = 12\text{ cm} and AC=16 cm AC = 16\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Intermediate
Triangle ACB with sides 16, 12, 20; right angle at BACB161220

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(12)2+(16)2=144+256=400=20 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(12)^2 + (16)^2} = \sqrt{144 + 256} = \sqrt{400} = 20\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(12)(16)=96 cm2 [ABC] = \frac{1}{2}(12)(16) = 96\text{ cm}^2 , and the semiperimeter is s=12+16+202=24 cm s = \frac{12 + 16 + 20}{2} = 24\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=9624=4 cm. r = \frac{[ABC]}{s} = \frac{96}{24} = 4\text{ cm}.
Final Answer: AB=20 cm,  Area=96 cm2,  r=4 cm AB = 20\text{ cm},\; \text{Area} = 96\text{ cm}^2,\; r = 4\text{ cm} .

24

[SAAT Limits, Derivatives, Definite Integrals & Area] The function f(x)=5x+3x−5 f(x) = \frac{5x + 3}{x - 5} is defined for x≠5 x \ne 5 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=6 f(x) = 6 .

Intermediate

Step 1 (Algebraic Inversion): Set y=5x+3x−5 y = \frac{5x + 3}{x - 5} and multiply both sides by (x−5) (x - 5) :
y(x−5)=5x+3  ⟹  xy−5y=5x+3  ⟹  x(y−5)=5y+3. y(x - 5) = 5x + 3 \implies xy - 5y = 5x + 3 \implies x(y - 5) = 5y + 3.

Step 2 (Domain of Inverse): Dividing by (y−5) (y - 5) and swapping x x and y y gives:
f−1(x)=5x+3x−5,with domain x∈R,  x≠5. f^{-1}(x) = \frac{5x + 3}{x - 5}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 5.

Step 3 (Solving f(x)=6 f(x) = 6 ): Since f f is self-inverse, x=f−1(6)=5(6)+3(6)−5=33 x = f^{-1}(6) = \frac{5(6) + 3}{(6) - 5} = 33 .
Final Answer: f−1(x)=5x+3x−5  (x≠5) f^{-1}(x) = \frac{5x + 3}{x - 5} \; (x \ne 5) , and x=33 x = 33 .

25

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] Solve the logarithmic equation log⁡2(x−6)+log⁡2(x+6)=log⁡2(108) \log_2(x - 6) + \log_2(x + 6) = \log_2(108) for x>6 x > 6 , showing why the negative root must be rejected.

Intermediate
Quadratic Intersection x² − 36 = 108 (Problem 25) — Coordinate plane with graph of y = x² − 36; marked points Valid x = 12 (12, 108)Quadratic Intersection x² − 36 = 108 (Problem 25)-10-551050100xyValid x = 12y = x² − 36

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>6 x > 6 :
log⁡2((x−6)(x+6))=log⁡2(108)  ⟹  x2−36=108. \log_2\big((x - 6)(x + 6)\big) = \log_2(108) \implies x^2 - 36 = 108.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=144  ⟹  x=±12 x^2 = 144 \implies x = \pm 12 . Since log⁡2(x−6) \log_2(x - 6) requires x−6>0  ⟺  x>6 x - 6 > 0 \iff x > 6 , the negative root x=−12 x = -12 is extraneous and must be rejected.
Final Answer: x=12 x = 12 .

26

[GAT Ratios, Percentages, Speed & Work-Rate Models] Find the equation of the tangent line to the curve y=x3−7x2+9x+2 y = x^3 - 7x^2 + 9x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Intermediate

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−7(2)2+9(2)+2=8−28+18+2=0. y(2) = 2^3 - 7(2)^2 + 9(2) + 2 = 8 - 28 + 18 + 2 = 0.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−14x+9. \frac{dy}{dx} = 3x^2 - 14x + 9.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−14(2)+9=−7 m = 3(4) - 14(2) + 9 = -7 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(0)=−7(x−2)  ⟹  y=−7x+(14). y - (0) = -7(x - 2) \implies y = -7x + (14).
Final Answer: y=−7x+(14) y = -7x + (14) , crossing the y y -axis at (0,14) (0, 14) .

27

[GAT Quantitative Comparisons & Shaded Geometry] An arithmetic sequence has first term u1=8 u_1 = 8 and common difference d=4 d = 4 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Intermediate

Step 1 (General Term Formula): For an arithmetic progression with first term u1=8 u_1 = 8 and common difference d=4 d = 4 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=8+11(4)=8+44=52. u_{12} = 8 + 11(4) = 8 + 44 = 52.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(8+52)=6(60)=360. S_{12} = \frac{12}{2}(8 + 52) = 6(60) = 360.
Final Answer: u12=52 u_{12} = 52 and S12=360 S_{12} = 360 .

28

[GAT & SAAT Data Interpretation, Counting & Probability] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=6 cm BC = 6\text{ cm} and AC=8 cm AC = 8\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Intermediate

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(6)2+(8)2=36+64=100=10 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(6)^2 + (8)^2} = \sqrt{36 + 64} = \sqrt{100} = 10\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(6)(8)=24 cm2 [ABC] = \frac{1}{2}(6)(8) = 24\text{ cm}^2 , and the semiperimeter is s=6+8+102=12 cm s = \frac{6 + 8 + 10}{2} = 12\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=2412=2 cm. r = \frac{[ABC]}{s} = \frac{24}{12} = 2\text{ cm}.
Final Answer: AB=10 cm,  Area=24 cm2,  r=2 cm AB = 10\text{ cm},\; \text{Area} = 24\text{ cm}^2,\; r = 2\text{ cm} .

29

[SAAT Logic, Polynomials, Matrices & Complex Numbers] The function f(x)=3x+10x−3 f(x) = \frac{3x + 10}{x - 3} is defined for x≠3 x \ne 3 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=4 f(x) = 4 .

Intermediate

Step 1 (Algebraic Inversion): Set y=3x+10x−3 y = \frac{3x + 10}{x - 3} and multiply both sides by (x−3) (x - 3) :
y(x−3)=3x+10  ⟹  xy−3y=3x+10  ⟹  x(y−3)=3y+10. y(x - 3) = 3x + 10 \implies xy - 3y = 3x + 10 \implies x(y - 3) = 3y + 10.

Step 2 (Domain of Inverse): Dividing by (y−3) (y - 3) and swapping x x and y y gives:
f−1(x)=3x+10x−3,with domain x∈R,  x≠3. f^{-1}(x) = \frac{3x + 10}{x - 3}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 3.

Step 3 (Solving f(x)=4 f(x) = 4 ): Since f f is self-inverse, x=f−1(4)=3(4)+10(4)−3=22 x = f^{-1}(4) = \frac{3(4) + 10}{(4) - 3} = 22 .
Final Answer: f−1(x)=3x+10x−3  (x≠3) f^{-1}(x) = \frac{3x + 10}{x - 3} \; (x \ne 3) , and x=22 x = 22 .

30

[SAAT Functions, Sequences, Exponentials & Logarithms] Solve the logarithmic equation log⁡2(x−4)+log⁡2(x+4)=log⁡2(48) \log_2(x - 4) + \log_2(x + 4) = \log_2(48) for x>4 x > 4 , showing why the negative root must be rejected.

Intermediate

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>4 x > 4 :
log⁡2((x−4)(x+4))=log⁡2(48)  ⟹  x2−16=48. \log_2\big((x - 4)(x + 4)\big) = \log_2(48) \implies x^2 - 16 = 48.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=64  ⟹  x=±8 x^2 = 64 \implies x = \pm 8 . Since log⁡2(x−4) \log_2(x - 4) requires x−4>0  ⟺  x>4 x - 4 > 0 \iff x > 4 , the negative root x=−8 x = -8 is extraneous and must be rejected.
Final Answer: x=8 x = 8 .

31

[SAAT Trigonometry, Conic Sections & 3D Vectors] Find the equation of the tangent line to the curve y=x3−5x2+8x+2 y = x^3 - 5x^2 + 8x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Intermediate
Curve & Tangent Line at x = 2 (Problem 31) — Coordinate plane with graph of y = f(x); marked points P(2, 6) (2, 6)Curve & Tangent Line at x = 2 (Problem 31)123510xyP(2, 6)y = f(x)

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−5(2)2+8(2)+2=8−20+16+2=6. y(2) = 2^3 - 5(2)^2 + 8(2) + 2 = 8 - 20 + 16 + 2 = 6.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−10x+8. \frac{dy}{dx} = 3x^2 - 10x + 8.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−10(2)+8=0 m = 3(4) - 10(2) + 8 = 0 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(6)=0(x−2)  ⟹  y=0x+(6). y - (6) = 0(x - 2) \implies y = 0x + (6).
Final Answer: y=0x+(6) y = 0x + (6) , crossing the y y -axis at (0,6) (0, 6) .

32

[SAAT Limits, Derivatives, Definite Integrals & Area] An arithmetic sequence has first term u1=6 u_1 = 6 and common difference d=3 d = 3 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Intermediate

Step 1 (General Term Formula): For an arithmetic progression with first term u1=6 u_1 = 6 and common difference d=3 d = 3 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=6+11(3)=6+33=39. u_{12} = 6 + 11(3) = 6 + 33 = 39.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(6+39)=6(45)=270. S_{12} = \frac{12}{2}(6 + 39) = 6(45) = 270.
Final Answer: u12=39 u_{12} = 39 and S12=270 S_{12} = 270 .

33

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=21 cm BC = 21\text{ cm} and AC=28 cm AC = 28\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Intermediate
Triangle ACB with sides 28, 21, 35; right angle at BACB282135

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(21)2+(28)2=441+784=1225=35 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(21)^2 + (28)^2} = \sqrt{441 + 784} = \sqrt{1225} = 35\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(21)(28)=294 cm2 [ABC] = \frac{1}{2}(21)(28) = 294\text{ cm}^2 , and the semiperimeter is s=21+28+352=42 cm s = \frac{21 + 28 + 35}{2} = 42\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=29442=7 cm. r = \frac{[ABC]}{s} = \frac{294}{42} = 7\text{ cm}.
Final Answer: AB=35 cm,  Area=294 cm2,  r=7 cm AB = 35\text{ cm},\; \text{Area} = 294\text{ cm}^2,\; r = 7\text{ cm} .

34

[GAT Ratios, Percentages, Speed & Work-Rate Models] The function f(x)=8x+9x−8 f(x) = \frac{8x + 9}{x - 8} is defined for x≠8 x \ne 8 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=9 f(x) = 9 .

Intermediate

Step 1 (Algebraic Inversion): Set y=8x+9x−8 y = \frac{8x + 9}{x - 8} and multiply both sides by (x−8) (x - 8) :
y(x−8)=8x+9  ⟹  xy−8y=8x+9  ⟹  x(y−8)=8y+9. y(x - 8) = 8x + 9 \implies xy - 8y = 8x + 9 \implies x(y - 8) = 8y + 9.

Step 2 (Domain of Inverse): Dividing by (y−8) (y - 8) and swapping x x and y y gives:
f−1(x)=8x+9x−8,with domain x∈R,  x≠8. f^{-1}(x) = \frac{8x + 9}{x - 8}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 8.

Step 3 (Solving f(x)=9 f(x) = 9 ): Since f f is self-inverse, x=f−1(9)=8(9)+9(9)−8=81 x = f^{-1}(9) = \frac{8(9) + 9}{(9) - 8} = 81 .
Final Answer: f−1(x)=8x+9x−8  (x≠8) f^{-1}(x) = \frac{8x + 9}{x - 8} \; (x \ne 8) , and x=81 x = 81 .

35

[GAT Quantitative Comparisons & Shaded Geometry] Solve the logarithmic equation log⁡2(x−2)+log⁡2(x+2)=log⁡2(12) \log_2(x - 2) + \log_2(x + 2) = \log_2(12) for x>2 x > 2 , showing why the negative root must be rejected.

Advanced
Quadratic Intersection x² − 4 = 12 (Problem 35) — Coordinate plane with graph of y = x² − 4; marked points Valid x = 4 (4, 12)Quadratic Intersection x² − 4 = 12 (Problem 35)-4-224-55101520xyValid x = 4y = x² − 4

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>2 x > 2 :
log⁡2((x−2)(x+2))=log⁡2(12)  ⟹  x2−4=12. \log_2\big((x - 2)(x + 2)\big) = \log_2(12) \implies x^2 - 4 = 12.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=16  ⟹  x=±4 x^2 = 16 \implies x = \pm 4 . Since log⁡2(x−2) \log_2(x - 2) requires x−2>0  ⟺  x>2 x - 2 > 0 \iff x > 2 , the negative root x=−4 x = -4 is extraneous and must be rejected.
Final Answer: x=4 x = 4 .

36

[GAT & SAAT Data Interpretation, Counting & Probability] Find the equation of the tangent line to the curve y=x3−3x2+7x+2 y = x^3 - 3x^2 + 7x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Advanced

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−3(2)2+7(2)+2=8−12+14+2=12. y(2) = 2^3 - 3(2)^2 + 7(2) + 2 = 8 - 12 + 14 + 2 = 12.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−6x+7. \frac{dy}{dx} = 3x^2 - 6x + 7.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−6(2)+7=7 m = 3(4) - 6(2) + 7 = 7 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(12)=7(x−2)  ⟹  y=7x+(−2). y - (12) = 7(x - 2) \implies y = 7x + (-2).
Final Answer: y=7x+(−2) y = 7x + (-2) , crossing the y y -axis at (0,−2) (0, -2) .

37

[SAAT Logic, Polynomials, Matrices & Complex Numbers] An arithmetic sequence has first term u1=4 u_1 = 4 and common difference d=10 d = 10 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Advanced

Step 1 (General Term Formula): For an arithmetic progression with first term u1=4 u_1 = 4 and common difference d=10 d = 10 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=4+11(10)=4+110=114. u_{12} = 4 + 11(10) = 4 + 110 = 114.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(4+114)=6(118)=708. S_{12} = \frac{12}{2}(4 + 114) = 6(118) = 708.
Final Answer: u12=114 u_{12} = 114 and S12=708 S_{12} = 708 .

38

[SAAT Functions, Sequences, Exponentials & Logarithms] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=15 cm BC = 15\text{ cm} and AC=20 cm AC = 20\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Advanced

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(15)2+(20)2=225+400=625=25 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(15)^2 + (20)^2} = \sqrt{225 + 400} = \sqrt{625} = 25\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(15)(20)=150 cm2 [ABC] = \frac{1}{2}(15)(20) = 150\text{ cm}^2 , and the semiperimeter is s=15+20+252=30 cm s = \frac{15 + 20 + 25}{2} = 30\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=15030=5 cm. r = \frac{[ABC]}{s} = \frac{150}{30} = 5\text{ cm}.
Final Answer: AB=25 cm,  Area=150 cm2,  r=5 cm AB = 25\text{ cm},\; \text{Area} = 150\text{ cm}^2,\; r = 5\text{ cm} .

39

[SAAT Trigonometry, Conic Sections & 3D Vectors] The function f(x)=6x+8x−6 f(x) = \frac{6x + 8}{x - 6} is defined for x≠6 x \ne 6 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=7 f(x) = 7 .

Advanced

Step 1 (Algebraic Inversion): Set y=6x+8x−6 y = \frac{6x + 8}{x - 6} and multiply both sides by (x−6) (x - 6) :
y(x−6)=6x+8  ⟹  xy−6y=6x+8  ⟹  x(y−6)=6y+8. y(x - 6) = 6x + 8 \implies xy - 6y = 6x + 8 \implies x(y - 6) = 6y + 8.

Step 2 (Domain of Inverse): Dividing by (y−6) (y - 6) and swapping x x and y y gives:
f−1(x)=6x+8x−6,with domain x∈R,  x≠6. f^{-1}(x) = \frac{6x + 8}{x - 6}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 6.

Step 3 (Solving f(x)=7 f(x) = 7 ): Since f f is self-inverse, x=f−1(7)=6(7)+8(7)−6=50 x = f^{-1}(7) = \frac{6(7) + 8}{(7) - 6} = 50 .
Final Answer: f−1(x)=6x+8x−6  (x≠6) f^{-1}(x) = \frac{6x + 8}{x - 6} \; (x \ne 6) , and x=50 x = 50 .

40

[SAAT Limits, Derivatives, Definite Integrals & Area] Solve the logarithmic equation log⁡2(x−7)+log⁡2(x+7)=log⁡2(147) \log_2(x - 7) + \log_2(x + 7) = \log_2(147) for x>7 x > 7 , showing why the negative root must be rejected.

Advanced

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>7 x > 7 :
log⁡2((x−7)(x+7))=log⁡2(147)  ⟹  x2−49=147. \log_2\big((x - 7)(x + 7)\big) = \log_2(147) \implies x^2 - 49 = 147.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=196  ⟹  x=±14 x^2 = 196 \implies x = \pm 14 . Since log⁡2(x−7) \log_2(x - 7) requires x−7>0  ⟺  x>7 x - 7 > 0 \iff x > 7 , the negative root x=−14 x = -14 is extraneous and must be rejected.
Final Answer: x=14 x = 14 .

41

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] Find the equation of the tangent line to the curve y=x3−8x2+6x+2 y = x^3 - 8x^2 + 6x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Advanced

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−8(2)2+6(2)+2=8−32+12+2=−10. y(2) = 2^3 - 8(2)^2 + 6(2) + 2 = 8 - 32 + 12 + 2 = -10.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−16x+6. \frac{dy}{dx} = 3x^2 - 16x + 6.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−16(2)+6=−14 m = 3(4) - 16(2) + 6 = -14 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(−10)=−14(x−2)  ⟹  y=−14x+(18). y - (-10) = -14(x - 2) \implies y = -14x + (18).
Final Answer: y=−14x+(18) y = -14x + (18) , crossing the y y -axis at (0,18) (0, 18) .

42

[GAT Ratios, Percentages, Speed & Work-Rate Models] An arithmetic sequence has first term u1=2 u_1 = 2 and common difference d=9 d = 9 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Advanced

Step 1 (General Term Formula): For an arithmetic progression with first term u1=2 u_1 = 2 and common difference d=9 d = 9 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=2+11(9)=2+99=101. u_{12} = 2 + 11(9) = 2 + 99 = 101.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(2+101)=6(103)=618. S_{12} = \frac{12}{2}(2 + 101) = 6(103) = 618.
Final Answer: u12=101 u_{12} = 101 and S12=618 S_{12} = 618 .

43

[GAT Quantitative Comparisons & Shaded Geometry] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=9 cm BC = 9\text{ cm} and AC=12 cm AC = 12\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Advanced

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(9)2+(12)2=81+144=225=15 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(9)^2 + (12)^2} = \sqrt{81 + 144} = \sqrt{225} = 15\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(9)(12)=54 cm2 [ABC] = \frac{1}{2}(9)(12) = 54\text{ cm}^2 , and the semiperimeter is s=9+12+152=18 cm s = \frac{9 + 12 + 15}{2} = 18\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=5418=3 cm. r = \frac{[ABC]}{s} = \frac{54}{18} = 3\text{ cm}.
Final Answer: AB=15 cm,  Area=54 cm2,  r=3 cm AB = 15\text{ cm},\; \text{Area} = 54\text{ cm}^2,\; r = 3\text{ cm} .

44

[GAT & SAAT Data Interpretation, Counting & Probability] The function f(x)=4x+7x−4 f(x) = \frac{4x + 7}{x - 4} is defined for x≠4 x \ne 4 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=5 f(x) = 5 .

Advanced

Step 1 (Algebraic Inversion): Set y=4x+7x−4 y = \frac{4x + 7}{x - 4} and multiply both sides by (x−4) (x - 4) :
y(x−4)=4x+7  ⟹  xy−4y=4x+7  ⟹  x(y−4)=4y+7. y(x - 4) = 4x + 7 \implies xy - 4y = 4x + 7 \implies x(y - 4) = 4y + 7.

Step 2 (Domain of Inverse): Dividing by (y−4) (y - 4) and swapping x x and y y gives:
f−1(x)=4x+7x−4,with domain x∈R,  x≠4. f^{-1}(x) = \frac{4x + 7}{x - 4}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 4.

Step 3 (Solving f(x)=5 f(x) = 5 ): Since f f is self-inverse, x=f−1(5)=4(5)+7(5)−4=27 x = f^{-1}(5) = \frac{4(5) + 7}{(5) - 4} = 27 .
Final Answer: f−1(x)=4x+7x−4  (x≠4) f^{-1}(x) = \frac{4x + 7}{x - 4} \; (x \ne 4) , and x=27 x = 27 .

45

[SAAT Logic, Polynomials, Matrices & Complex Numbers] Solve the logarithmic equation log⁡2(x−5)+log⁡2(x+5)=log⁡2(75) \log_2(x - 5) + \log_2(x + 5) = \log_2(75) for x>5 x > 5 , showing why the negative root must be rejected.

Advanced

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>5 x > 5 :
log⁡2((x−5)(x+5))=log⁡2(75)  ⟹  x2−25=75. \log_2\big((x - 5)(x + 5)\big) = \log_2(75) \implies x^2 - 25 = 75.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=100  ⟹  x=±10 x^2 = 100 \implies x = \pm 10 . Since log⁡2(x−5) \log_2(x - 5) requires x−5>0  ⟺  x>5 x - 5 > 0 \iff x > 5 , the negative root x=−10 x = -10 is extraneous and must be rejected.
Final Answer: x=10 x = 10 .

46

[SAAT Functions, Sequences, Exponentials & Logarithms] Find the equation of the tangent line to the curve y=x3−6x2+5x+2 y = x^3 - 6x^2 + 5x + 2 at the point where x=2 x = 2 , and determine where this tangent crosses the y y -axis.

Advanced

Step 1 (Point Evaluation): Substitute x=2 x = 2 into the curve equation to find the y y -coordinate of tangency:
y(2)=23−6(2)2+5(2)+2=8−24+10+2=−4. y(2) = 2^3 - 6(2)^2 + 5(2) + 2 = 8 - 24 + 10 + 2 = -4.

Step 2 (Derivative & Gradient): Differentiate with respect to x x using the power rule:
dydx=3x2−12x+5. \frac{dy}{dx} = 3x^2 - 12x + 5.
Evaluating at x=2 x = 2 gives the instantaneous tangent gradient m=3(4)−12(2)+5=−7 m = 3(4) - 12(2) + 5 = -7 .

Step 3 (Tangent Line Equation): Using the point-slope formula y−y0=m(x−x0) y - y_0 = m(x - x_0) :
y−(−4)=−7(x−2)  ⟹  y=−7x+(10). y - (-4) = -7(x - 2) \implies y = -7x + (10).
Final Answer: y=−7x+(10) y = -7x + (10) , crossing the y y -axis at (0,10) (0, 10) .

47

[SAAT Trigonometry, Conic Sections & 3D Vectors] An arithmetic sequence has first term u1=7 u_1 = 7 and common difference d=8 d = 8 . Find the 12 12 -th term u12 u_{12} and the exact sum of the first 12 12 terms S12 S_{12} .

Advanced

Step 1 (General Term Formula): For an arithmetic progression with first term u1=7 u_1 = 7 and common difference d=8 d = 8 , the n n -th term is given by un=u1+(n−1)d u_n = u_1 + (n - 1)d . Substituting n=12 n = 12 :
u12=7+11(8)=7+88=95. u_{12} = 7 + 11(8) = 7 + 88 = 95.

Step 2 (Series Sum Formula): Using Gauss's pairing formula Sn=n2(u1+un) S_n = \frac{n}{2}(u_1 + u_n) for n=12 n = 12 :
S12=122(7+95)=6(102)=612. S_{12} = \frac{12}{2}(7 + 95) = 6(102) = 612.
Final Answer: u12=95 u_{12} = 95 and S12=612 S_{12} = 612 .

48

[SAAT Limits, Derivatives, Definite Integrals & Area] In right-angled triangle ABC ABC with ∠C=90∘ \angle C = 90^\circ , the legs have lengths BC=24 cm BC = 24\text{ cm} and AC=32 cm AC = 32\text{ cm} . Calculate the hypotenuse AB AB , the area of △ABC \triangle ABC , and the inradius r r of its inscribed circle.

Advanced

Step 1 (Pythagorean Theorem): Since ∠C=90∘ \angle C = 90^\circ , the hypotenuse AB AB satisfies:
AB=BC2+AC2=(24)2+(32)2=576+1024=1600=40 cm. AB = \sqrt{BC^2 + AC^2} = \sqrt{(24)^2 + (32)^2} = \sqrt{576 + 1024} = \sqrt{1600} = 40\text{ cm}.

Step 2 (Area & Semiperimeter): The area is [ABC]=12(24)(32)=384 cm2 [ABC] = \frac{1}{2}(24)(32) = 384\text{ cm}^2 , and the semiperimeter is s=24+32+402=48 cm s = \frac{24 + 32 + 40}{2} = 48\text{ cm} .

Step 3 (Inradius): Using the identity [ABC]=r⋅s [ABC] = r \cdot s :
r=[ABC]s=38448=8 cm. r = \frac{[ABC]}{s} = \frac{384}{48} = 8\text{ cm}.
Final Answer: AB=40 cm,  Area=384 cm2,  r=8 cm AB = 40\text{ cm},\; \text{Area} = 384\text{ cm}^2,\; r = 8\text{ cm} .

49

[GAT Arithmetic, Number Sense & High-Speed Shortcuts] The function f(x)=2x+6x−2 f(x) = \frac{2x + 6}{x - 2} is defined for x≠2 x \ne 2 . Find the inverse function f−1(x) f^{-1}(x) , state its domain, and solve f(x)=3 f(x) = 3 .

Advanced

Step 1 (Algebraic Inversion): Set y=2x+6x−2 y = \frac{2x + 6}{x - 2} and multiply both sides by (x−2) (x - 2) :
y(x−2)=2x+6  ⟹  xy−2y=2x+6  ⟹  x(y−2)=2y+6. y(x - 2) = 2x + 6 \implies xy - 2y = 2x + 6 \implies x(y - 2) = 2y + 6.

Step 2 (Domain of Inverse): Dividing by (y−2) (y - 2) and swapping x x and y y gives:
f−1(x)=2x+6x−2,with domain x∈R,  x≠2. f^{-1}(x) = \frac{2x + 6}{x - 2}, \quad \text{with domain } x \in \mathbb{R},\; x \ne 2.

Step 3 (Solving f(x)=3 f(x) = 3 ): Since f f is self-inverse, x=f−1(3)=2(3)+6(3)−2=12 x = f^{-1}(3) = \frac{2(3) + 6}{(3) - 2} = 12 .
Final Answer: f−1(x)=2x+6x−2  (x≠2) f^{-1}(x) = \frac{2x + 6}{x - 2} \; (x \ne 2) , and x=12 x = 12 .

50

[GAT Ratios, Percentages, Speed & Work-Rate Models] Solve the logarithmic equation log⁡2(x−3)+log⁡2(x+3)=log⁡2(27) \log_2(x - 3) + \log_2(x + 3) = \log_2(27) for x>3 x > 3 , showing why the negative root must be rejected.

Advanced

Step 1 (Combine Logarithms): Using the logarithmic product identity log⁡2(u)+log⁡2(v)=log⁡2(uv) \log_2(u) + \log_2(v) = \log_2(uv) on the domain x>3 x > 3 :
log⁡2((x−3)(x+3))=log⁡2(27)  ⟹  x2−9=27. \log_2\big((x - 3)(x + 3)\big) = \log_2(27) \implies x^2 - 9 = 27.

Step 2 (Solve Quadratic & Check Domain): Rearranging gives x2=36  ⟹  x=±6 x^2 = 36 \implies x = \pm 6 . Since log⁡2(x−3) \log_2(x - 3) requires x−3>0  ⟺  x>3 x - 3 > 0 \iff x > 3 , the negative root x=−6 x = -6 is extraneous and must be rejected.
Final Answer: x=6 x = 6 .

AI-assisted, human-reviewed: Questions and walkthroughs are developed with AI assistance and reviewed by senior educators. Report an error here ↗

Generate authentic non-calculator English GAT Quantitative and SAAT Mathematics simulations under official 1-minute-per-question Qiyas timing.

Full official exam paper

Full-length non-calculator Qiyas English simulations covering GAT Quantitative Reasoning (including Column A/B Quantitative Comparisons) and SAAT Secondary Mathematics.

AI-assisted, human-reviewed: Questions and walkthroughs are developed with AI assistance and reviewed by senior educators. Report an error here ↗
↓

Downloads

Download English-medium GAT Quantitative and SAAT Mathematics formula sheets, non-calculator speed drills, and full practice booklets.

PDF · ready now

English GAT & SAAT Complete STEM Revision Guide

All eight GAT Quantitative and SAAT Mathematics modules with non-calculator mental shortcuts and past-paper solutions.

DOCX · on request

Native Word packet

Editable .docx revision packet with native equation-editor formulas ready for print or classroom training.

Worksheet Library

Timed non-calculator English GAT and SAAT Mathematics topical worksheets with rapid solution strategies.

Loading worksheet library…

Mock Exam

--:--