AS Level Mathematics · ClipSAT

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AS Level Mathematics

Boards · Cambridge / Edexcel Level · AS · Year 1 Chapters · 20 Explorers · 3 interactive
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About AS Level

🗺 Cambridge AS Level Mathematics 9709 — Syllabus Map

PaperClipSAT ChapterKey Topics
P1 Pure 1Algebra — Indices, Surds & QuadraticsLaws of indices, surds, completing the square, discriminant
Simultaneous Equations & InequalitiesLinear/nonlinear systems, modulus inequalities
Graphs & Transformationsy=f(x) transformations: translations, stretches, reflections
Coordinate GeometryLine segments, circles, intersection
Circular MeasureRadians, arc length, sector area, segment
TrigonometryExact values, identities, solving equations in given range
Series & Binomial TheoremAP/GP, sum to infinity, (a+b)n(a+b)^n expansion
Differentiation & IntegrationGradient, tangent/normal, stationary points, definite integral, area
P1Functions: Composite & InverseDomain, range, fgfg, f−1f^{-1}
M1 MechanicsKinematicsSUVAT, velocity-time graphs, calculus kinematics
Forces & Equilibrium / Newton's LawsResultant, components, F=maF=ma, connected particles
Energy, Work & PowerKE, PE, work-energy principle, power
S1 StatisticsRepresentation of DataHistograms, cumulative freq., mean, variance, SD, box plots
Permutations & Combinationsn!n!, nPr^nP_r, nCr^nC_r, arrangement with restrictions
Discrete Random VariablesProbability distribution, E(X)E(X), Var(X)\text{Var}(X)
Binomial DistributionX∼B(n,p)X\sim B(n,p), cumulative probabilities, mean & variance
Normal DistributionX∼N(μ,σ2)X\sim N(\mu,\sigma^2), standardisation, inverse normal

AS Level Mathematics is the first year of the A Level, offered by boards such as Cambridge (9709) and Edexcel. It blends Pure Mathematics with an introduction to Statistics and Mechanics.

What it covers

The Pure core runs through indices and surds, quadratics, coordinate geometry, graphs and transformations, trigonometry, and the first ideas of differentiation and integration. Applied units add probability, data handling and kinematics.

Pure
algebra · geometry · calculus
Statistics
data · probability
Mechanics
kinematics · forces
Calculator
allowed (most papers)
▲ How to use this course

Each chapter pairs a reference panel with worked examples; the explorers make slope, transformations and the gradient idea visual. Finish with the 50-problem set, then export it as a worksheet.

⚠ Cambridge 9709 Exam Rules & Accuracy Guidelines
Accuracy standard: Non-exact answers must be given to 3 significant figures, or 1 decimal place for angles in degrees, unless specified otherwise in the question. Do not round prematurely in intermediate steps.

Command words: 'Show that' demands complete algebraic working with no skipped steps. 'Hence' means you must use the preceding result — alternate methods receive no credit.

Angle modes: Circular measure and calculus strictly require radian mode. Working in degrees for arc length or calculus formulas voids the entire solution.
Bar chart: Cambridge 9709 AS Paper Mark Distribution with categories: P1 Pure 1 (75), M1 Mechanics (50), S1 Stats 1 (50)019385675P1 Pure 175M1 Mechanics50S1 Stats 150Cambridge 9709 AS Paper Mark Distribution
Cambridge AS Level Mathematics 9709 Paper Marks: Pure Mathematics 1 (75 marks, 60% of AS) paired with Mechanics (50 marks, 40%) or Probability & Statistics (50 marks, 40%).
A student computes the volume of a cylinder using r=3.2 cmr = 3.2\text{ cm} and h=7.85 cmh = 7.85\text{ cm}. The raw calculator display shows 252.518...252.518.... How should the final answer be reported according to Cambridge AS Level guidelines?
Unless otherwise specified, non-exact numerical answers must be given to 3 significant figures. Rounding 252.518...252.518... to 3 s.f. gives 253 cm3253\text{ cm}^3. Giving 1 or 2 s.f., or excessive decimal places without justification, incurs an accuracy penalty (A1).
📝 Chapter Quiz
1

Indices, Surds & Quadratics

📌 Algebra — Indices, Surds & Quadratics P1  ·  Laws of indices  ·  Surds  ·  Completing the square  ·  Discriminant & nature of roots

The laws of indices, simplifying and rationalising surds, and the full toolkit for quadratics — factorising, completing the square and the formula.

▲ Reference — Algebra core

aman=am+n a^{m}a^{n}=a^{m+n} , a−n=1an a^{-n}=\tfrac{1}{a^{n}} , a1/n=an a^{1/n}=\sqrt[n]{a} . Quadratic formula x=−b±b2−4ac2a x=\dfrac{-b\pm\sqrt{b^{2}-4ac}}{2a} ; the discriminant b2−4ac b^{2}-4ac fixes the number of real roots.

Indices
aman=am+n a^{m}a^{n}=a^{m+n}
Surds
ab=ab \sqrt{ab}=\sqrt{a}\sqrt{b}
Completing square
(x+b2)2−b24 (x+\tfrac{b}{2})^{2}-\tfrac{b^{2}}{4}
Discriminant
b2−4ac b^{2}-4ac
Coordinate plane; marked points (-0.5, 0) (-0.5, 0), (3, 0) (3, 0), V(1.25, -6.125) (1.25, -6.125)-4-3-2-11234-4-224xy(-0.5, 0)(3, 0)V(1.25, -6.125)
Parabola y=2x2−5x−3y = 2x^2 - 5x - 3 intersecting the xx-axis at x=−12x = -\frac{1}{2} and x=3x = 3, with vertex at (1.25,−6.125)(1.25, -6.125).
⚠ Common Traps & Exam Pitfalls
Completing the square when a≠1a \neq 1: Factor aa from the quadratic and linear terms before halving the coefficient: ax2+bx+c=a[x2+bax]+c=a(x+b2a)2−a(b2a)2+cax^2+bx+c = a\left[x^2+\tfrac{b}{a}x\right]+c = a\left(x+\tfrac{b}{2a}\right)^2 - a\left(\tfrac{b}{2a}\right)^2 + c. Forgetting to multiply the subtracted square by aa is the most frequent algebraic slip.

Discriminant phrasing: 'Real roots' means b2−4ac≥0b^2-4ac \ge 0 (includes repeated roots). 'Two distinct real roots' strictly requires b2−4ac>0b^2-4ac > 0. 'No real roots' means b2−4ac<0b^2-4ac < 0. If the leading coefficient contains a parameter kk, remember k≠0k \neq 0 for the equation to be quadratic.

Surd conjugates: To rationalise ab+c\frac{a}{b+\sqrt{c}}, multiply numerator and denominator by b−cb-\sqrt{c}. Expanding (b+c)(b−c)=b2−c(b+\sqrt{c})(b-\sqrt{c}) = b^2 - c eliminates the radical completely.
Worked example 1.A

Simplify 12 \sqrt{12} .

4⋅3=23. \sqrt{4\cdot3}=2\sqrt{3}.

Worked example 1.B

Complete the square for x2+4x x^{2}+4x .

(x+2)2−4. (x+2)^{2}-4.

Solve the quadratic equation 2x2−5x−3=02x^2 - 5x - 3 = 0 by completing the square. State the vertex of the corresponding parabola y=2x2−5x−3y = 2x^2 - 5x - 3.
Factor 2 from the first two terms: 2(x2−52x)−3=02\left(x^2 - \tfrac{5}{2}x\right) - 3 = 0. Halve the coefficient of xx: 12(−52)=−54\tfrac{1}{2}\left(-\tfrac{5}{2}\right) = -\tfrac{5}{4}. Complete the square: 2(x−54)2−2(2516)−3=0⇒2(x−54)2−258−248=0⇒2(x−54)2=4982\left(x - \tfrac{5}{4}\right)^2 - 2\left(\tfrac{25}{16}\right) - 3 = 0\Rightarrow 2\left(x - \tfrac{5}{4}\right)^2 - \tfrac{25}{8} - \tfrac{24}{8} = 0\Rightarrow 2\left(x - \tfrac{5}{4}\right)^2 = \tfrac{49}{8}. Divide by 2: (x−54)2=4916\left(x - \tfrac{5}{4}\right)^2 = \tfrac{49}{16}. Take square roots: x−54=±74⇒x=5+74=3x - \tfrac{5}{4} = \pm\tfrac{7}{4}\Rightarrow x = \tfrac{5+7}{4} = 3 or x=5−74=−12x = \tfrac{5-7}{4} = -\tfrac{1}{2}. The vertex is (54,−498)=(1.25,−6.125)\left(\tfrac{5}{4}, -\tfrac{49}{8}\right) = (1.25, -6.125).
Express 3+52−5\dfrac{3+\sqrt{5}}{2-\sqrt{5}} in the form p+q5p + q\sqrt{5}, where pp and qq are rational numbers to be found.
Multiply numerator and denominator by the conjugate of the denominator, 2+52+\sqrt{5}: 3+52−5×2+52+5=(3+5)(2+5)22−(5)2\dfrac{3+\sqrt{5}}{2-\sqrt{5}} \times \dfrac{2+\sqrt{5}}{2+\sqrt{5}} = \dfrac{(3+\sqrt{5})(2+\sqrt{5})}{2^2 - (\sqrt{5})^2} Expanding the numerator: 3(2)+35+25+(5)2=6+55+5=11+553(2) + 3\sqrt{5} + 2\sqrt{5} + (\sqrt{5})^2 = 6 + 5\sqrt{5} + 5 = 11 + 5\sqrt{5}. The denominator is 4−5=−14 - 5 = -1. Therefore: 11+55−1=−11−55\dfrac{11+5\sqrt{5}}{-1} = -11 - 5\sqrt{5} Thus p=−11p = -11 and q=−5q = -5.
Find the set of values of the constant kk for which the equation kx2+4x+(k−3)=0kx^2 + 4x + (k-3) = 0 has real roots.
For real roots, the discriminant Δ=b2−4ac≥0\Delta = b^2 - 4ac \ge 0. Here a=ka = k, b=4b = 4, c=k−3c = k-3: Δ=42−4(k)(k−3)=16−4k2+12k≥0\Delta = 4^2 - 4(k)(k-3) = 16 - 4k^2 + 12k \ge 0 Divide the entire inequality by −4-4, reversing the inequality sign: k2−3k−4≤0k^2 - 3k - 4 \le 0 Factor the quadratic: (k−4)(k+1)≤0(k - 4)(k + 1) \le 0. The critical values are k=−1k = -1 and k=4k = 4. Since the parabola opens upward, the product is ≤0\le 0 between the roots: −1≤k≤4-1 \le k \le 4. Note that if k=0k = 0, the equation becomes the linear equation 4x−3=04x - 3 = 0, which has one real root x=34x = \tfrac{3}{4}, so k=0k = 0 is included. Thus, the solution set is −1≤k≤4-1 \le k \le 4.
📝 Chapter Quiz
2

Simultaneous Equations & Inequalities

📌 Simultaneous Equations & Inequalities P1  ·  Linear & non-linear systems  ·  Quadratic inequalities  ·  Modulus function

Solving linear and linear-with-quadratic systems, and linear and quadratic inequalities.

▲ Reference — Systems & inequalities

Solve a linear system by substitution or elimination; for a linear–quadratic pair, substitute the linear equation into the quadratic. A quadratic inequality is solved by finding the roots and testing the sign of each interval.

Linear system
substitute / eliminate
Linear–quadratic
substitute the line
Sign rule
flip ≤ \le when ÷(−) \div(-)
Quadratic ineq.
roots then test
Coordinate plane; marked points (3.24, 7.47) (3.24, 7.47), (-1.24, -1.47) (-1.24, -1.47)-4-3-2-11234-4-224xy(3.24, 7.47)(-1.24, -1.47)
Parabola y=x2−3y = x^2 - 3 and line y=2x+1y = 2x + 1 intersecting at x=1±5x = 1 \pm \sqrt{5}.
⚠ Common Traps & Exam Pitfalls
Quadratic inequalities format: Never write x2>9⇒x>±3x^2 > 9 \Rightarrow x > \pm 3. Always find critical roots and sketch the parabola. For ax2+bx+c>0ax^2+bx+c > 0 (with a>0a > 0), the solution consists of two separate inequalities connected by 'or': x<r1x < r_1 or x>r2x > r_2. Combining them into r1>x>r2r_1 > x > r_2 loses the final mark.

Pairing coordinates in systems: After finding two values of xx, substitute each into the linear equation to find the corresponding yy. Pair them explicitly as (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2). Substituting into the quadratic equation often creates false phantom pairings.

Modulus validity check: In equations like ∣ax+b∣=cx+d|ax+b| = cx+d, any candidate solution that makes cx+d<0cx+d < 0 is extraneous and must be discarded because absolute values are non-negative.
Worked example 2.A

Solve x+y=5 x+y=5 , x−y=1 x-y=1 .

Add: 2x=6 2x=6 :

x=3, y=2. x=3,\ y=2.

Worked example 2.B

Solve x2−4<0 x^{2}-4<0 .

Roots ±2 \pm2 , curve below axis between them:

−2<x<2. -2<x<2.

Solve the simultaneous equations: 2x+y=72x + y = 7 x2+xy=12x^2 + xy = 12
From the linear equation, express yy in terms of xx: y=7−2xy = 7 - 2x. Substitute into the second equation: x2+x(7−2x)=12⇒x2+7x−2x2=12⇒−x2+7x−12=0x^2 + x(7 - 2x) = 12 \Rightarrow x^2 + 7x - 2x^2 = 12 \Rightarrow -x^2 + 7x - 12 = 0 Multiply by −1-1: x2−7x+12=0x^2 - 7x + 12 = 0. Factor: (x−3)(x−4)=0(x - 3)(x - 4) = 0, giving x=3x = 3 or x=4x = 4. For x=3x = 3: y=7−2(3)=1y = 7 - 2(3) = 1. For x=4x = 4: y=7−2(4)=−1y = 7 - 2(4) = -1. The solutions are (3,1)(3, 1) and (4,−1)(4, -1).
Find the set of values of xx satisfying the inequality 2x2−7x+3≤02x^2 - 7x + 3 \le 0.
Find the critical values where 2x2−7x+3=02x^2 - 7x + 3 = 0. Factor the quadratic: (2x−1)(x−3)=0(2x - 1)(x - 3) = 0, so the roots are x=12x = \tfrac{1}{2} and x=3x = 3. Since the coefficient of x2x^2 is positive (a=2>0a = 2 > 0), the parabola opens upward. The quadratic is less than or equal to zero between and including the roots. Therefore, the solution set is 12≤x≤3\tfrac{1}{2} \le x \le 3.
Solve the inequality ∣3x−5∣<2∣x+1∣|3x - 5| < 2|x + 1|.
Both sides are non-negative, so we can square both sides: ∣3x−5∣2<4∣x+1∣2⇒9x2−30x+25<4(x2+2x+1)|3x - 5|^2 < 4|x + 1|^2 \Rightarrow 9x^2 - 30x + 25 < 4(x^2 + 2x + 1) Expand and simplify: 9x2−30x+25<4x2+8x+4⇒5x2−38x+21<09x^2 - 30x + 25 < 4x^2 + 8x + 4 \Rightarrow 5x^2 - 38x + 21 < 0 Factor: (5x−3)(x−7)<0(5x - 3)(x - 7) < 0. The critical values are x=35x = \tfrac{3}{5} and x=7x = 7. Since the parabola opens upward, the expression is strictly negative between the roots: 35<x<7\tfrac{3}{5} < x < 7.
📝 Chapter Quiz
3

Graphs & Transformations

📌 Graphs & Transformations P1  ·  Sketching curves  ·  f(x+a)f(x+a), f(ax)f(ax), −f(x)-f(x), f(−x)f(-x)  ·  Identifying transformations

Sketching standard curves and applying translations, reflections and stretches.

▲ Reference — Transformations of y=f(x) y=f(x)

f(x)+a f(x)+a shifts up by a a ; f(x−a) f(x-a) shifts right by a a ; −f(x) -f(x) reflects in the x x -axis; af(x) af(x) stretches vertically by factor a a .

The grey curve is y=sin⁡x y=\sin x ; the indigo curve is y=sin⁡(x−h)+k y=\sin(x-h)+k . Slide h h and k k to translate it.

⊙ Explorer · Translating a graphinteractive
translation (h, k)—

Inside the function, x−h x-h moves right; outside, +k +k moves up.

Up by a
f(x)+a f(x)+a
Right by a
f(x−a) f(x-a)
Reflect (x-axis)
−f(x) -f(x)
Stretch
af(x) af(x)
Coordinate plane; marked points Origin (0,0) (0, 0), V(2, -3) (2, -3), (3, -1) (3, -1)-4-3-2-11234-4-224xyOrigin (0,0)V(2, -3)(3, -1)
Transformation of y=x2y = x^2 to y=2(x−2)2−3y = 2(x-2)^2 - 3: translated by (2−3)\begin{pmatrix}2\\-3\end{pmatrix} and stretched vertically by scale factor 2.
⚠ Common Traps & Exam Pitfalls
Horizontal vs vertical operations: Operations inside the argument f(… )f(\dots) affect xx inversely: f(x−a)f(x-a) translates right by +a+a, and f(kx)f(kx) stretches horizontally by scale factor 1k\tfrac{1}{k}. Operations outside affect yy directly: af(x)af(x) stretches vertically by aa, and f(x)+cf(x)+c shifts up by cc.

Order of horizontal transformations: For f(ax+b)f(ax+b), always factor the bracket: f(a(x+ba))f\left(a(x + \tfrac{b}{a})\right). This represents a horizontal stretch by scale factor 1a\tfrac{1}{a} followed by a translation by vector (−ba0)\begin{pmatrix}-\frac{b}{a}\\0\end{pmatrix}, OR a translation of −b-b followed by stretch of 1a\tfrac{1}{a}. Stating transformations in the wrong order loses all marks.

Reflection axes: y=−f(x)y = -f(x) is a reflection in the xx-axis (y→−yy \to -y). y=f(−x)y = f(-x) is a reflection in the yy-axis (x→−xx \to -x).
Worked example 3.A

Describe y=(x−2)2 y=(x-2)^{2} relative to y=x2 y=x^{2} .

It is a translation 2 2 units to the right.

Worked example 3.B

Describe y=−x2 y=-x^{2} relative to y=x2 y=x^{2} .

A reflection in the x x -axis.

The curve y=f(x)y = f(x) has a stationary point at (4,−6)(4, -6). State the coordinates of the corresponding stationary point on the curve: (a) y=f(x+3)+2y = f(x+3) + 2, (b) y=3f(2x)y = 3f(2x), (c) y=−f(−x)y = -f(-x).
(a) y=f(x+3)+2y = f(x+3)+2 translates 3 units left and 2 units up: (4−3,−6+2)=(1,−4)(4-3, -6+2) = (1, -4).
(b) y=3f(2x)y = 3f(2x) stretches horizontally by 12\tfrac{1}{2} and vertically by 3: (4×12,−6×3)=(2,−18)\left(4 \times \tfrac{1}{2}, -6 \times 3\right) = (2, -18).
(c) y=−f(−x)y = -f(-x) reflects in both axes (point reflection through the origin): (−4,−(−6))=(−4,6)(-4, -(-6)) = (-4, 6).
The curve y=x2−6x+5y = x^2 - 6x + 5 can be mapped to y=x2y = x^2 by a sequence of two geometric transformations. Express the equation in vertex form, state the vertex, and describe fully each transformation.
Complete the square: y=(x−3)2−9+5=(x−3)2−4y = (x-3)^2 - 9 + 5 = (x-3)^2 - 4. The vertex of the parabola is (3,−4)(3, -4). To map y=(x−3)2−4y = (x-3)^2 - 4 back to y=x2y = x^2, we must translate the graph 3 units to the left and 4 units upwards. In vector notation, this is a single translation by (−34)\begin{pmatrix}-3\\4\end{pmatrix}, or two sequential transformations: (1) Translation by vector (−30)\begin{pmatrix}-3\\0\end{pmatrix} (3 units left), and (2) Translation by vector (04)\begin{pmatrix}0\\4\end{pmatrix} (4 units up).
📝 Chapter Quiz
4

Coordinate Geometry

📌 Coordinate Geometry P1  ·  Line equations  ·  Circle equation & properties  ·  Tangent to a circle

Straight lines — gradient, midpoint, distance and equations — and the equation of a circle.

▲ Reference — Lines & circles

Gradient m=y2−y1x2−x1 m=\dfrac{y_2-y_1}{x_2-x_1} ; line y−y1=m(x−x1) y-y_1=m(x-x_1) . A circle with centre (a,b) (a,b) and radius r r is (x−a)2+(y−b)2=r2 (x-a)^{2}+(y-b)^{2}=r^{2} .

Adjust gradient m m and intercept b b of y=mx+b y=mx+b ; the amber dots are the intercepts.

⊙ Explorer · Gradient & interceptsinteractive
gradient—
y-intercept—
x-intercept—

Perpendicular gradients satisfy m1m2=−1 m_1m_2=-1 .

Gradient
y2−y1x2−x1 \dfrac{y_2-y_1}{x_2-x_1}
Line
y−y1=m(x−x1) y-y_1=m(x-x_1)
Distance
Δx2+Δy2 \sqrt{\Delta x^{2}+\Delta y^{2}}
Circle
(x−a)2+(y−b)2=r2 (x-a)^{2}+(y-b)^{2}=r^{2}
CircleP(7, 2)Q(-1, 2)C(3, -1)
Circle with centre (3,−1)(3, -1) and radius r=5r = 5, passing through P(7,2)P(7, 2) with equation (x−3)2+(y+1)2=25(x-3)^2 + (y+1)^2 = 25.
⚠ Common Traps & Exam Pitfalls
Circle center signs: The equation is (x−a)2+(y−b)2=r2(x-a)^2 + (y-b)^2 = r^2. In (x−3)2+(y+1)2=25(x-3)^2 + (y+1)^2 = 25, the center is (+3,−1)(+3, -1), NOT (−3,1)(-3, 1). Also, the right-hand side is r2r^2, so the radius is 25=5\sqrt{25} = 5, not 25.

Perpendicular lines: Gradients satisfy m1m2=−1m_1 m_2 = -1, giving m⊥=−1mm_{\perp} = -\frac{1}{m}. A frequent error is forgetting the negative sign (reciprocal without negation).

Circle geometry properties: (1) The tangent to a circle is perpendicular to the radius at the point of contact. (2) The perpendicular bisector of any chord passes through the center of the circle. (3) The angle in a semicircle is a right angle.
Worked example 4.A

Find the gradient through (1,2) (1,2) and (4,11) (4,11) .

11−24−1=3. \frac{11-2}{4-1}=3.

Worked example 4.B

State the centre of (x−2)2+(y+3)2=25 (x-2)^{2}+(y+3)^{2}=25 .

(2, −3). (2,\,-3).

Find the equation of the perpendicular bisector of the line segment joining A(−2,5)A(-2, 5) and B(4,−3)B(4, -3). Give your answer in the form ax+by+c=0ax + by + c = 0, where a,b,ca, b, c are integers.
1. Midpoint of ABAB: M=(−2+42,5−32)=(1,1)M = \left(\tfrac{-2+4}{2}, \tfrac{5-3}{2}\right) = (1, 1).
2. Gradient of ABAB: mAB=−3−54−(−2)=−86=−43m_{AB} = \tfrac{-3-5}{4-(-2)} = \tfrac{-8}{6} = -\tfrac{4}{3}.
3. Gradient of perpendicular bisector: m⊥=−1−4/3=34m_{\perp} = -\tfrac{1}{-4/3} = \tfrac{3}{4}.
4. Equation of line passing through M(1,1)M(1, 1): y−1=34(x−1)⇒4(y−1)=3(x−1)⇒4y−4=3x−3y - 1 = \tfrac{3}{4}(x - 1) \Rightarrow 4(y - 1) = 3(x - 1) \Rightarrow 4y - 4 = 3x - 3 Rearrange to standard integer form: 3x−4y+1=03x - 4y + 1 = 0.
The circle CC has equation x2+y2−6x+4y−12=0x^2 + y^2 - 6x + 4y - 12 = 0. (a) Find the coordinates of the centre and the exact radius of CC. (b) Find the equation of the tangent to CC at the point P(6,2)P(6, 2).
(a) Complete the squares for xx and yy: (x2−6x+9)+(y2+4y+4)=12+9+4⇒(x−3)2+(y+2)2=25(x^2 - 6x + 9) + (y^2 + 4y + 4) = 12 + 9 + 4 \Rightarrow (x - 3)^2 + (y + 2)^2 = 25 The centre is (3,−2)(3, -2) and the radius is 25=5\sqrt{25} = 5.
(b) The gradient of the radius from centre (3,−2)(3, -2) to P(6,2)P(6, 2) is: mrad=2−(−2)6−3=43m_{\text{rad}} = \dfrac{2 - (-2)}{6 - 3} = \dfrac{4}{3} The tangent is perpendicular to the radius, so its gradient is mtan=−34m_{\text{tan}} = -\tfrac{3}{4}. Using point-slope form with P(6,2)P(6, 2): y−2=−34(x−6)⇒4(y−2)=−3(x−6)⇒4y−8=−3x+18⇒3x+4y−26=0y - 2 = -\tfrac{3}{4}(x - 6) \Rightarrow 4(y - 2) = -3(x - 6) \Rightarrow 4y - 8 = -3x + 18 \Rightarrow 3x + 4y - 26 = 0 In slope-intercept form: y=−34x+132y = -\tfrac{3}{4}x + \tfrac{13}{2}.
📝 Chapter Quiz
5

Trigonometry

📌 Trigonometry P1  ·  Exact trig values  ·  sin⁡2θ+cos⁡2θ=1\sin^2\theta+\cos^2\theta=1  ·  Solving trig equations in a range

Exact values, the identity linking sine and cosine, and solving simple trigonometric equations.

▲ Reference — Trig essentials

sin⁡2θ+cos⁡2θ=1 \sin^{2}\theta+\cos^{2}\theta=1 and tan⁡θ=sin⁡θcos⁡θ \tan\theta=\dfrac{\sin\theta}{\cos\theta} . Exact values: sin⁡30∘=12 \sin30^{\circ}=\tfrac12 , cos⁡30∘=32 \cos30^{\circ}=\tfrac{\sqrt3}{2} , sin⁡60∘=32 \sin60^{\circ}=\tfrac{\sqrt3}{2} . The sine and cosine curves have period 360∘ 360^{\circ} .

Identity
sin⁡2θ+cos⁡2θ=1 \sin^{2}\theta+\cos^{2}\theta=1
Tangent
sin⁡θcos⁡θ \tfrac{\sin\theta}{\cos\theta}
Exact
sin⁡60∘=32 \sin60^{\circ}=\tfrac{\sqrt3}{2}
Period
360∘ 360^{\circ}
Unit circle diagramxy30°(0.866, 0.5)
Unit circle showing angle 210∘210^\circ in Quadrant III with reference angle 30∘30^\circ and coordinates (−32,−12)\left(-\frac{\sqrt{3}}{2}, -\frac{1}{2}\right).
⚠ Common Traps & Exam Pitfalls
Never divide by trig terms: In equations such as 2sin⁡θcos⁡θ=sin⁡θ2\sin\theta\cos\theta = \sin\theta, dividing by sin⁡θ\sin\theta destroys the roots where sin⁡θ=0\sin\theta = 0. Always rearrange to one side and factor: sin⁡θ(2cos⁡θ−1)=0\sin\theta(2\cos\theta - 1) = 0.

Compound angle domain: When solving an equation like cos⁡(2x−30∘)=12\cos(2x - 30^\circ) = \tfrac{1}{2} for 0∘≤x≤180∘0^\circ \le x \le 180^\circ, first transform the domain for u=2x−30∘u = 2x - 30^\circ: −30∘≤u≤330∘-30^\circ \le u \le 330^\circ. Find all valid values for uu within this adjusted window, then solve for xx.

Identity substitution: Always check if replacing sin⁡2θ\sin^2\theta with 1−cos⁡2θ1 - \cos^2\theta (or vice-versa) creates a single-variable quadratic in cos⁡θ\cos\theta or sin⁡θ\sin\theta.
Worked example 5.A

Solve sin⁡θ=12 \sin\theta=\tfrac12 for 0∘≤θ≤180∘ 0^{\circ}\le\theta\le180^{\circ} .

θ=30∘, 150∘. \theta=30^{\circ},\ 150^{\circ}.

Worked example 5.B

State the exact value of sin⁡60∘ \sin60^{\circ} .

32. \tfrac{\sqrt3}{2}.

Solve the equation 2cos⁡2θ−sin⁡θ−1=02\cos^2\theta - \sin\theta - 1 = 0 for 0∘≤θ≤360∘0^\circ \le \theta \le 360^\circ.
Use the Pythagorean identity cos⁡2θ=1−sin⁡2θ\cos^2\theta = 1 - \sin^2\theta: 2(1−sin⁡2θ)−sin⁡θ−1=0⇒2−2sin⁡2θ−sin⁡θ−1=0⇒−2sin⁡2θ−sin⁡θ+1=02(1 - \sin^2\theta) - \sin\theta - 1 = 0 \Rightarrow 2 - 2\sin^2\theta - \sin\theta - 1 = 0 \Rightarrow -2\sin^2\theta - \sin\theta + 1 = 0 Multiply by −1-1: 2sin⁡2θ+sin⁡θ−1=02\sin^2\theta + \sin\theta - 1 = 0. Factor: (2sin⁡θ−1)(sin⁡θ+1)=0(2\sin\theta - 1)(\sin\theta + 1) = 0.
1. 2sin⁡θ−1=0⇒sin⁡θ=122\sin\theta - 1 = 0 \Rightarrow \sin\theta = \tfrac{1}{2}. In [0∘,360∘][0^\circ, 360^\circ], θ=30∘\theta = 30^\circ or 180∘−30∘=150∘180^\circ - 30^\circ = 150^\circ.
2. sin⁡θ+1=0⇒sin⁡θ=−1\sin\theta + 1 = 0 \Rightarrow \sin\theta = -1. In [0∘,360∘][0^\circ, 360^\circ], θ=270∘\theta = 270^\circ.
The complete solution set is θ=30∘,150∘,270∘\theta = 30^\circ, 150^\circ, 270^\circ.
Prove the identity: cos⁡θ1−sin⁡θ−cos⁡θ1+sin⁡θ≡2tan⁡θ\dfrac{\cos\theta}{1 - \sin\theta} - \dfrac{\cos\theta}{1 + \sin\theta} \equiv 2\tan\theta
Start with the left-hand side and write over a common denominator: LHS=cos⁡θ(1+sin⁡θ)−cos⁡θ(1−sin⁡θ)(1−sin⁡θ)(1+sin⁡θ)\text{LHS} = \dfrac{\cos\theta(1 + \sin\theta) - \cos\theta(1 - \sin\theta)}{(1 - \sin\theta)(1 + \sin\theta)} Expand the numerator: cos⁡θ+cos⁡θsin⁡θ−cos⁡θ+cos⁡θsin⁡θ=2cos⁡θsin⁡θ\cos\theta + \cos\theta\sin\theta - \cos\theta + \cos\theta\sin\theta = 2\cos\theta\sin\theta.
Expand the denominator: 1−sin⁡2θ=cos⁡2θ1 - \sin^2\theta = \cos^2\theta.
Substitute both back: LHS=2cos⁡θsin⁡θcos⁡2θ=2sin⁡θcos⁡θ=2tan⁡θ=RHS\text{LHS} = \dfrac{2\cos\theta\sin\theta}{\cos^2\theta} = \dfrac{2\sin\theta}{\cos\theta} = 2\tan\theta = \text{RHS} Q.E.D.
Solve the equation tan⁡(2x−20∘)=3\tan(2x - 20^\circ) = \sqrt{3} for 0∘≤x≤180∘0^\circ \le x \le 180^\circ.
Let u=2x−20∘u = 2x - 20^\circ. As 0∘≤x≤180∘0^\circ \le x \le 180^\circ, the domain for uu is −20∘≤u≤340∘-20^\circ \le u \le 340^\circ.
Since tan⁡60∘=3\tan 60^\circ = \sqrt{3}, the principal solution is u=60∘u = 60^\circ. Tangent has a period of 180∘180^\circ, so the solutions for uu within [−20∘,340∘][-20^\circ, 340^\circ] are: u=60∘,u=60∘+180∘=240∘u = 60^\circ, \quad u = 60^\circ + 180^\circ = 240^\circ Now solve for x=u+20∘2x = \tfrac{u + 20^\circ}{2}:
1. For u=60∘u = 60^\circ: x=60∘+20∘2=40∘x = \tfrac{60^\circ + 20^\circ}{2} = 40^\circ.
2. For u=240∘u = 240^\circ: x=240∘+20∘2=130∘x = \tfrac{240^\circ + 20^\circ}{2} = 130^\circ.
Both solutions lie within [0∘,180∘][0^\circ, 180^\circ]. Thus x=40∘x = 40^\circ or x=130∘x = 130^\circ.
📝 Chapter Quiz
6

Differentiation & Integration

📌 Differentiation & Integration P1  ·  Gradient & stationary points  ·  Tangent & normal  ·  Definite integral & area under curve

The gradient of a curve from first principles, the power rule for differentiation, and reversing it to integrate.

▲ Reference — The power rule

ddxxn=nxn−1 \dfrac{d}{dx}x^{n}=nx^{n-1} ; the gradient at a point is the value of dydx \tfrac{dy}{dx} there. Integration reverses this: ∫xn dx=xn+1n+1+C \displaystyle\int x^{n}\,dx=\dfrac{x^{n+1}}{n+1}+C for n≠−1 n\neq-1 .

The amber line is a secant from x=1 x=1 to x=1+h x=1+h on y=x2 y=x^{2} . Shrink h h and watch its slope approach the tangent gradient, 2 2 .

⊙ Explorer · Secant → tangentinteractive
secant gradient—

The secant gradient is 2+h 2+h ; as h→0 h\to0 it tends to the tangent gradient 2 2 .

Differentiate
nxn−1 nx^{n-1}
Gradient
value of dydx \tfrac{dy}{dx}
Integrate
xn+1n+1+C \tfrac{x^{n+1}}{n+1}+C
Definite
F(b)−F(a) F(b)-F(a)
Coordinate plane; marked points Max(-1, 2) (-1, 2), Min(1, -2) (1, -2), (0, 0) (0, 0)-4-3-2-11234-4-224xyMax(-1, 2)Min(1, -2)(0, 0)
Cubic curve y=x3−3xy = x^3 - 3x showing local maximum at (−1,2)(-1, 2) and local minimum at (1,−2)(1, -2).
⚠ Common Traps & Exam Pitfalls
Algebraic preparation: Express all algebraic fractions and surds in index form before differentiating or integrating: 3x2=3x−2\frac{3}{x^2} = 3x^{-2}, 4x=4x1/24\sqrt{x} = 4x^{1/2}, 12x=12x−1/2\frac{1}{2\sqrt{x}} = \frac{1}{2}x^{-1/2}. Differentiating denominators directly without rewriting produces invalid derivatives.

Tangent vs Normal: The tangent line has gradient mtan=dydxm_{\text{tan}} = \frac{dy}{dx}. The normal line is perpendicular, having gradient mnorm=−1mtanm_{\text{norm}} = -\frac{1}{m_{\text{tan}}}. Both lines pass through the exact same point (x1,y1)(x_1, y_1) on the curve.

Area between curves: Area is ∫ab(ytop−ybottom) dx\int_a^b (y_{\text{top}} - y_{\text{bottom}})\,dx. If a curve crosses the xx-axis within the limits of integration, integrating across the roots will result in positive and negative areas cancelling out. You must integrate each section separately and sum the positive areas.
Worked example 6.A

Differentiate y=x2+3x y=x^{2}+3x .

dydx=2x+3. \frac{dy}{dx}=2x+3.

Worked example 6.B

Evaluate ∫012x dx \displaystyle\int_{0}^{1} 2x\,dx .

[x2]01=1. \left[x^{2}\right]_{0}^{1}=1.

A curve has equation y=2x3−9x2+12x+1y = 2x^3 - 9x^2 + 12x + 1. (a) Find the coordinates of both stationary points. (b) Determine the nature of each stationary point using the second derivative d2ydx2\frac{d^2y}{dx^2}.
(a) Find dydx\frac{dy}{dx}: dydx=6x2−18x+12\dfrac{dy}{dx} = 6x^2 - 18x + 12 Set dydx=0\frac{dy}{dx} = 0: 6(x2−3x+2)=0⇒6(x−1)(x−2)=06(x^2 - 3x + 2) = 0 \Rightarrow 6(x - 1)(x - 2) = 0, giving x=1x = 1 and x=2x = 2.
When x=1x = 1: y=2(1)−9(1)+12(1)+1=6y = 2(1) - 9(1) + 12(1) + 1 = 6. Point is (1,6)(1, 6).
When x=2x = 2: y=2(8)−9(4)+12(2)+1=16−36+24+1=5y = 2(8) - 9(4) + 12(2) + 1 = 16 - 36 + 24 + 1 = 5. Point is (2,5)(2, 5).
(b) Second derivative: d2ydx2=12x−18\dfrac{d^2y}{dx^2} = 12x - 18 At x=1x = 1: d2ydx2=12(1)−18=−6<0\frac{d^2y}{dx^2} = 12(1) - 18 = -6 < 0, so (1,6)(1, 6) is a local maximum.
At x=2x = 2: d2ydx2=12(2)−18=+6>0\frac{d^2y}{dx^2} = 12(2) - 18 = +6 > 0, so (2,5)(2, 5) is a local minimum.
Find the exact area of the region enclosed between the curve y=4x−x2y = 4x - x^2 and the line y=xy = x.
Find points of intersection: 4x−x2=x⇒3x−x2=0⇒x(3−x)=04x - x^2 = x \Rightarrow 3x - x^2 = 0 \Rightarrow x(3 - x) = 0 The curves intersect at x=0x = 0 and x=3x = 3. Between 00 and 33, the curve y=4x−x2y = 4x - x^2 lies above the line y=xy = x.
The enclosed area is: A=∫03[(4x−x2)−x] dx=∫03(3x−x2) dxA = \int_0^3 \left[(4x - x^2) - x\right]\,dx = \int_0^3 (3x - x^2)\,dx Integrate: A=[3x22−x33]03=(3(9)2−273)−0=272−9=27−182=92=4.5A = \left[\dfrac{3x^2}{2} - \dfrac{x^3}{3}\right]_0^3 = \left(\dfrac{3(9)}{2} - \dfrac{27}{3}\right) - 0 = \dfrac{27}{2} - 9 = \dfrac{27 - 18}{2} = \dfrac{9}{2} = 4.5
Find the equation of the normal to the curve y=4x+2xy = \dfrac{4}{\sqrt{x}} + 2x at the point where x=4x = 4.
Rewrite in index form: y=4x−1/2+2xy = 4x^{-1/2} + 2x.
At x=4x = 4: y=4(4−1/2)+2(4)=4(12)+8=2+8=10y = 4(4^{-1/2}) + 2(4) = 4\left(\tfrac{1}{2}\right) + 8 = 2 + 8 = 10. Point of contact is (4,10)(4, 10).
Differentiate: dydx=4(−12x−3/2)+2=−2x−3/2+2=−2x3/2+2\dfrac{dy}{dx} = 4\left(-\tfrac{1}{2}x^{-3/2}\right) + 2 = -2x^{-3/2} + 2 = -\dfrac{2}{x^{3/2}} + 2 At x=4x = 4: x3/2=(4)3=8x^{3/2} = (\sqrt{4})^3 = 8. Thus: mtan=−28+2=−14+2=74m_{\text{tan}} = -\dfrac{2}{8} + 2 = -\dfrac{1}{4} + 2 = \dfrac{7}{4} The normal has gradient mnorm=−17/4=−47m_{\text{norm}} = -\dfrac{1}{7/4} = -\dfrac{4}{7}.
Using point (4,10)(4, 10): y−10=−47(x−4)⇒7(y−10)=−4(x−4)⇒7y−70=−4x+16⇒4x+7y−86=0y - 10 = -\dfrac{4}{7}(x - 4) \Rightarrow 7(y - 10) = -4(x - 4) \Rightarrow 7y - 70 = -4x + 16 \Rightarrow 4x + 7y - 86 = 0
📝 Chapter Quiz
7

Statistics & Probability

📌 Statistics & Probability S1  ·  Basic probability  ·  Conditional probability  ·  Tree diagrams  ·  Venn diagrams

Summarising data with averages and spread, and the probability of simple events.

▲ Reference — Data & chance

Mean is total over count; the median is the middle of the ordered data; range is largest minus smallest. Probability =favourabletotal =\dfrac{\text{favourable}}{\text{total}} .

Mean
∑xn \dfrac{\sum x}{n}
Median
middle value
Range
max − min
Probability
favtotal \dfrac{\text{fav}}{\text{total}}
Venn diagramAB
Venn diagram showing two independent events AA and BB with P(A)=0.4P(A) = 0.4, P(B)=0.5P(B) = 0.5, and P(A∩B)=0.2P(A \cap B) = 0.2.
⚠ Common Traps & Exam Pitfalls
Mutually exclusive vs Independent: These two concepts are mutually contradictory for non-trivial events. Mutually exclusive means they cannot happen together: P(A∩B)=0P(A \cap B) = 0. Independent means the occurrence of one does not affect the probability of the other: P(A∩B)=P(A)P(B)P(A \cap B) = P(A)P(B). If P(A)>0P(A) > 0 and P(B)>0P(B) > 0, mutually exclusive events can never be independent.

Conditional probability denominator: In P(A∣B)=P(A∩B)P(B)P(A|B) = \frac{P(A \cap B)}{P(B)}, the denominator is always the given condition P(B)P(B), never P(A)P(A).

Sampling without replacement: In successive draws without replacement, remember to reduce both the favorable count and the total count on second branches (e.g. 59×48\frac{5}{9} \times \frac{4}{8}).
Worked example 7.A

Find the mean of 2, 4, 6, 8 2,\,4,\,6,\,8 .

204=5. \frac{20}{4}=5.

Worked example 7.B

Find the median of 3, 7, 9, 12, 20 3,\,7,\,9,\,12,\,20 .

9. 9.

Events AA and BB are such that P(A)=0.6P(A) = 0.6, P(B)=0.5P(B) = 0.5, and P(A∪B)=0.8P(A \cup B) = 0.8. Find P(A∩B)P(A \cap B), calculate P(A∣B)P(A|B), and determine whether AA and BB are independent.
1. Use the addition rule: P(A∪B)=P(A)+P(B)−P(A∩B)⇒0.8=0.6+0.5−P(A∩B)⇒P(A∩B)=1.1−0.8=0.3P(A \cup B) = P(A) + P(B) - P(A \cap B) \Rightarrow 0.8 = 0.6 + 0.5 - P(A \cap B) \Rightarrow P(A \cap B) = 1.1 - 0.8 = 0.3.
2. Conditional probability: P(A∣B)=P(A∩B)P(B)=0.30.5=0.6P(A|B) = \dfrac{P(A \cap B)}{P(B)} = \dfrac{0.3}{0.5} = 0.6 3. Check for independence: P(A∩B)=0.3P(A \cap B) = 0.3 and P(A)×P(B)=0.6×0.5=0.30P(A) \times P(B) = 0.6 \times 0.5 = 0.30. Since P(A∩B)=P(A)P(B)P(A \cap B) = P(A)P(B) (or equivalently P(A∣B)=P(A)=0.6P(A|B) = P(A) = 0.6), events AA and BB are independent.
A bag contains 5 red and 4 green marbles. Three marbles are drawn at random without replacement. Find the probability that: (a) all three are red, (b) at least two are red.
Total marbles = 9. Number of ways to choose 3 marbles = (93)=9×8×73×2×1=84\binom{9}{3} = \tfrac{9 \times 8 \times 7}{3 \times 2 \times 1} = 84.
(a) All 3 are red: (53)=10\binom{5}{3} = 10. Probability: P(all red)=1084=542≈0.119P(\text{all red}) = \dfrac{10}{84} = \dfrac{5}{42} \approx 0.119 (b) 'At least two red' means exactly 2 red and 1 green, or exactly 3 red:
Ways for 2 red, 1 green: (52)×(41)=10×4=40\binom{5}{2} \times \binom{4}{1} = 10 \times 4 = 40.
Ways for 3 red: (53)=10\binom{5}{3} = 10.
Total favorable outcomes: 40+10=5040 + 10 = 50.
Probability: P(≥2 red)=5084=2542≈0.595P(\ge 2 \text{ red}) = \dfrac{50}{84} = \dfrac{25}{42} \approx 0.595
📝 Chapter Quiz
8

Functions: Composite & Inverse

📌 Functions: Composite & Inverse P1  ·  Domain & range  ·  Composite fg(x)fg(x)  ·  Inverse f−1(x)f^{-1}(x)  ·  Modulus function

Beyond graphs, AS treats functions formally — domain, range, composition and inverses.

▲ Reference — Functions

fg(x)=f(g(x)) fg(x)=f(g(x)) . The inverse f−1 f^{-1} reverses f f and reflects its graph in the line y=x y=x ; the range of f f is the domain of f−1 f^{-1} .

Composite
fg(x) fg(x)
Inverse
swap & solve
Reflection
in y=x y=x
Range
domain of f−1 f^{-1}
Coordinate plane; marked points (0, -3) (0, -3), (3, 3) (3, 3), (-3, 0) (-3, 0)-4-3-2-11234-4-224xy(0, -3)(3, 3)(-3, 0)
Linear function f(x)=2x−3f(x) = 2x - 3 and its inverse f−1(x)=x+32f^{-1}(x) = \frac{x+3}{2}, intersecting at (3,3)(3, 3) along the reflection line y=xy = x.
⚠ Common Traps & Exam Pitfalls
One-to-one condition for inverses: An inverse function f−1f^{-1} exists if and only if ff is one-to-one over its given domain. For a quadratic function f(x)=a(x−h)2+kf(x) = a(x-h)^2 + k, the domain must be restricted to one side of the vertex (either x≥hx \ge h or x≤hx \le h). If the domain is all real numbers, the inverse does not exist.

Domain of f−1f^{-1}: The domain of f−1f^{-1} is always the range of ff. Stating x∈Rx \in \mathbb{R} when the original function had a bounded range (e.g. f(x)≥4f(x) \ge 4) loses the final mark.

Order of composition: fg(x)fg(x) denotes f(g(x))f(g(x)) — evaluate gg first, then insert into ff. In general, fg(x)≠gf(x)fg(x) \neq gf(x). Furthermore, for fgfg to be defined, the range of gg must lie entirely within the domain of ff.
Worked example 8.A

If f(x)=3x−2 f(x)=3x-2 , find f−1(x) f^{-1}(x) .

f−1(x)=x+23. f^{-1}(x)=\frac{x+2}{3}.

Worked example — Composite functions

Given f(x)=x+1f(x)=\sqrt{x+1} (x≥−1x\geq-1) and g(x)=2x−3g(x)=2x-3, find (a) fg(x)fg(x), (b) the range of fgfg.

(a) fg(x)=f(2x−3)=2x−3+1=2x−2fg(x)=f(2x-3)=\sqrt{2x-3+1}=\sqrt{2x-2}, domain x≥1x\geq1.

(b) As x≥1x\geq1, 2x−2≥02x-2\geq0, so range of fgfg is fg(x)≥0fg(x)\geq0.

The function ff is defined by f(x)=x2−6x+13f(x) = x^2 - 6x + 13 for x≥3x \ge 3. (a) State the range of ff. (b) Find an expression for f−1(x)f^{-1}(x) and state the domain and range of f−1f^{-1}.
(a) Complete the square: f(x)=(x−3)2−9+13=(x−3)2+4f(x) = (x - 3)^2 - 9 + 13 = (x - 3)^2 + 4. Since x≥3x \ge 3, (x−3)2≥0(x - 3)^2 \ge 0, so the minimum value is f(3)=4f(3) = 4. The range of ff is f(x)≥4f(x) \ge 4.
(b) Set y=(x−3)2+4y = (x - 3)^2 + 4. Rearrange for xx: y−4=(x−3)2⇒x−3=+y−4(since x≥3)y - 4 = (x - 3)^2 \Rightarrow x - 3 = +\sqrt{y - 4} \quad (\text{since } x \ge 3) x=3+y−4x = 3 + \sqrt{y - 4} Therefore, f−1(x)=3+x−4f^{-1}(x) = 3 + \sqrt{x - 4}.
Domain of f−1f^{-1} is x≥4x \ge 4 (the range of ff), and range of f−1f^{-1} is f−1(x)≥3f^{-1}(x) \ge 3 (the domain of ff).
Functions gg and hh are defined by g(x)=2x−1g(x) = 2x - 1 for x∈Rx \in \mathbb{R}, and h(x)=6x−2h(x) = \dfrac{6}{x - 2} for x≠2x \neq 2. (a) Find an expression for hg(x)hg(x) in simplest form. (b) Solve the equation hg(x)=g(x)hg(x) = g(x).
(a) Substitute g(x)g(x) into hh: hg(x)=h(2x−1)=6(2x−1)−2=62x−3(x≠32)hg(x) = h(2x - 1) = \dfrac{6}{(2x - 1) - 2} = \dfrac{6}{2x - 3} \quad \left(x \neq \tfrac{3}{2}\right) (b) Set hg(x)=g(x)hg(x) = g(x): 62x−3=2x−1⇒6=(2x−1)(2x−3)\dfrac{6}{2x - 3} = 2x - 1 \Rightarrow 6 = (2x - 1)(2x - 3) Expand the right-hand side: 6=4x2−8x+3⇒4x2−8x−3=06 = 4x^2 - 8x + 3 \Rightarrow 4x^2 - 8x - 3 = 0 Factor: (2x−3)(2x+1)=0(2x - 3)(2x + 1) = 0.
Since x≠32x \neq \tfrac{3}{2} for hg(x)hg(x) to be defined, the value x=32x = \tfrac{3}{2} is excluded.
Therefore, the unique solution is 2x+1=0⇒x=−122x + 1 = 0 \Rightarrow x = -\tfrac{1}{2}.
📝 Chapter Quiz
9

Circular Measure

📌 Circular Measure P1  ·  Radians ↔ degrees  ·  Arc length s=rθs=r\theta  ·  Sector area A=12r2θA=\tfrac{1}{2}r^2\theta  ·  Segment area

Angles measured in radians give clean formulas for arc length and sector area.

▲ Reference — Radians

180∘=π 180^{\circ}=\pi radians. Arc length s=rθ s=r\theta ; sector area A=12r2θ A=\tfrac12 r^{2}\theta , with θ \theta in radians.

Convert
180∘=π 180^{\circ}=\pi
Arc length
s=rθ s=r\theta
Sector
12r2θ \tfrac12 r^{2}\theta
Full turn
2π 2\pi
CircleABO
Circle with centre OO and radius r=8 cmr = 8\text{ cm}, showing sector OABOAB subtending central angle θ=1.2 rad\theta = 1.2\text{ rad} and chord ABAB.
⚠ Common Traps & Exam Pitfalls
Calculator in Radian mode: Formulas s=rθs = r\theta, A=12r2θA = \tfrac{1}{2}r^2\theta, and AΔ=12r2sin⁡θA_{\Delta} = \tfrac{1}{2}r^2\sin\theta are strictly valid only when θ\theta is in radians. If your calculator is in degree mode when evaluating sin⁡(1.2)\sin(1.2), you will evaluate the sine of 1.2∘1.2^\circ instead of 1.2 rad1.2\text{ rad}, wiping out all accuracy marks.

Perimeter of a sector: The perimeter of a sector consists of the curved arc length PLUS the two straight radii: P=rθ+2rP = r\theta + 2r. Overlooking the two radii (+2r+2r) is the single most common slip in Cambridge circular measure questions.

Major vs Minor: Always double check whether the question specifies the minor or major segment/sector. For the major sector, the central angle is 2π−θ2\pi - \theta.
Worked example 9.A

Find the arc length when r=5 r=5 and θ=π3 \theta=\tfrac{\pi}{3} .

s=5⋅π3=5π3. s=5\cdot\frac{\pi}{3}=\frac{5\pi}{3}.

Worked example — Segment area

A sector OAB has radius 8 cm and angle ∠AOB=1.2\angle AOB=1.2 rad. Find the area of the minor segment cut off by chord AB.

Sector area=12(8)2(1.2)=38.4 cm2.\text{Sector area}=\tfrac{1}{2}(8)^2(1.2)=38.4\text{ cm}^2.Triangle area=12(8)2sin⁡(1.2)=32sin⁡(1.2)≈29.56 cm2.\text{Triangle area}=\tfrac{1}{2}(8)^2\sin(1.2)=32\sin(1.2)\approx29.56\text{ cm}^2.Segment=38.4−29.56≈8.84 cm2.\text{Segment}=38.4-29.56\approx8.84\text{ cm}^2.

A circle has radius 8 cm8\text{ cm}. A sector of this circle has a total perimeter of 28 cm28\text{ cm}. Find the angle of the sector in radians, and calculate the exact area of the sector.
The perimeter of a sector is given by P=s+2r=rθ+2rP = s + 2r = r\theta + 2r.
Substitute P=28P = 28 and r=8r = 8: 28=8θ+2(8)⇒28=8θ+16⇒8θ=12⇒θ=128=1.5 radians28 = 8\theta + 2(8) \Rightarrow 28 = 8\theta + 16 \Rightarrow 8\theta = 12 \Rightarrow \theta = \dfrac{12}{8} = 1.5\text{ radians} The area of the sector is: A=12r2θ=12(82)(1.5)=12(64)(1.5)=32×1.5=48 cm2A = \dfrac{1}{2}r^2\theta = \dfrac{1}{2}(8^2)(1.5) = \dfrac{1}{2}(64)(1.5) = 32 \times 1.5 = 48\text{ cm}^2
In a circle of radius 10 cm10\text{ cm}, chord ABAB subtends an angle of θ=2π3\theta = \tfrac{2\pi}{3} radians at the centre OO. Find: (a) the exact length of chord ABAB, (b) the exact area of the minor segment bounded by chord ABAB and minor arc ABAB, in terms of π\pi and 3\sqrt{3}.
(a) Use the cosine rule in triangle OABOAB with OA=OB=10OA = OB = 10 and ∠AOB=2π3=120∘\angle AOB = \tfrac{2\pi}{3} = 120^\circ: AB2=102+102−2(10)(10)cos⁡(2π3)=100+100−200(−12)=200+100=300AB^2 = 10^2 + 10^2 - 2(10)(10)\cos\left(\tfrac{2\pi}{3}\right) = 100 + 100 - 200\left(-\tfrac{1}{2}\right) = 200 + 100 = 300 Thus AB=300=103 cmAB = \sqrt{300} = 10\sqrt{3}\text{ cm}.
(b) Area of sector OABOAB: Asector=12r2θ=12(102)(2π3)=100π3 cm2A_{\text{sector}} = \dfrac{1}{2}r^2\theta = \dfrac{1}{2}(10^2)\left(\tfrac{2\pi}{3}\right) = \dfrac{100\pi}{3}\text{ cm}^2 Area of triangle OABOAB: AΔ=12r2sin⁡θ=12(102)sin⁡(2π3)=50(32)=253 cm2A_{\Delta} = \dfrac{1}{2}r^2\sin\theta = \dfrac{1}{2}(10^2)\sin\left(\tfrac{2\pi}{3}\right) = 50\left(\dfrac{\sqrt{3}}{2}\right) = 25\sqrt{3}\text{ cm}^2 Area of minor segment: Asegment=Asector−AΔ=100π3−253=100π−7533 cm2A_{\text{segment}} = A_{\text{sector}} - A_{\Delta} = \dfrac{100\pi}{3} - 25\sqrt{3} = \dfrac{100\pi - 75\sqrt{3}}{3}\text{ cm}^2
📝 Chapter Quiz
10

Series & the Binomial Theorem

📌 Series & Binomial Theorem P1  ·  AP & GP formulas  ·  Sum to infinity  ·  (a+b)n(a+b)^n expansion  ·  General term

Arithmetic and geometric progressions, and the binomial expansion of (a+b)n (a+b)^{n} .

▲ Reference — Series

AP sum Sn=n2(2a+(n−1)d) S_n=\tfrac{n}{2}\big(2a+(n-1)d\big) ; GP sum Sn=a(1−rn)1−r S_n=\tfrac{a(1-r^{n})}{1-r} ; binomial (1+x)n=1+nx+n(n−1)2x2+⋯ (1+x)^{n}=1+nx+\tfrac{n(n-1)}{2}x^{2}+\cdots .

AP term
a+(n−1)d a+(n-1)d
AP sum
n2(2a+(n−1)d) \tfrac{n}{2}(2a+(n-1)d)
GP sum
a(1−rn)1−r \tfrac{a(1-r^{n})}{1-r}
Binomial
nCr {}^nC_r
Bar chart: Decaying Geometric Sequence with categories: u1 (12), u2 (8), u3 (5.33), u4 (3.56), u5 (2.37)Decaying Geometric Sequence03691215Term value12u18u25.33u33.56u42.37u5
Decaying terms of a convergent geometric sequence with a=12a = 12 and r=23r = \frac{2}{3}, approaching zero with sum to infinity S∞=36S_\infty = 36.
⚠ Common Traps & Exam Pitfalls
Convergence condition for S∞S_\infty: The sum to infinity S∞=a1−rS_\infty = \frac{a}{1-r} is valid if and only if ∣r∣<1|r| < 1 (−1<r<1-1 < r < 1). If a question states that a series has a sum to infinity, you can establish an inequality for unknown parameters: −1<r<1-1 < r < 1.

Binomial powers on coefficients: In (a+bx)n(a+bx)^n, the term involving xrx^r contains (bx)r=brxr(bx)^r = b^r x^r. Writing 3x23x^2 instead of (3x)2=9x2(3x)^2 = 9x^2 or −2x3-2x^3 instead of (−2x)3=−8x3(-2x)^3 = -8x^3 destroys the coefficient.

Term formulas index offset: In an AP, the nn-th term has n−1n-1 common differences: un=a+(n−1)du_n = a + (n-1)d. In a GP, un=arn−1u_n = ar^{n-1}. Do not confuse the nn-th term with the sum SnS_n.
Worked example 10.A

Find the sum of the first 10 10 terms of 2,5,8,… 2,5,8,\dots

S10=102(4+27)=155. S_{10}=\frac{10}{2}\big(4+27\big)=155.

Worked example — Geometric series & sum to infinity

A geometric series has first term 12 and common ratio 23\tfrac{2}{3}. Find (a) the 5th term, (b) S∞S_\infty.

(a) u5=12⋅(23)4=12⋅1681=6427u_5=12\cdot(\tfrac{2}{3})^4=12\cdot\tfrac{16}{81}=\tfrac{64}{27}.

(b) S∞=121−23=1213=36S_\infty=\dfrac{12}{1-\tfrac{2}{3}}=\dfrac{12}{\tfrac{1}{3}}=36.

In an arithmetic progression, the 3rd term is 1414 and the 7th term is 3434. (a) Find the first term aa and the common difference dd. (b) Find the sum of the first 2525 terms.
(a) Use un=a+(n−1)du_n = a + (n - 1)d: u3=a+2d=14u_3 = a + 2d = 14 u7=a+6d=34u_7 = a + 6d = 34 Subtract the first equation from the second: 4d=20⇒d=54d = 20 \Rightarrow d = 5.
Substitute back: a+2(5)=14⇒a=4a + 2(5) = 14 \Rightarrow a = 4.
(b) Use the sum formula Sn=n2(2a+(n−1)d)S_n = \tfrac{n}{2}\left(2a + (n - 1)d\right) with n=25n = 25: S25=252(2(4)+24(5))=252(8+120)=252(128)=25×64=1600S_{25} = \dfrac{25}{2}\left(2(4) + 24(5)\right) = \dfrac{25}{2}(8 + 120) = \dfrac{25}{2}(128) = 25 \times 64 = 1600
Find the coefficient of x3x^3 in the expansion of (2−3x)(1+2x)6(2 - 3x)(1 + 2x)^6.
Expand (1+2x)6(1 + 2x)^6 up to the x3x^3 term: (60)=1\binom{6}{0} = 1 (61)(2x)=6(2x)=12x\binom{6}{1}(2x) = 6(2x) = 12x (62)(2x)2=15(4x2)=60x2\binom{6}{2}(2x)^2 = 15(4x^2) = 60x^2 (63)(2x)3=20(8x3)=160x3\binom{6}{3}(2x)^3 = 20(8x^3) = 160x^3 So (1+2x)6=1+12x+60x2+160x3+⋯(1 + 2x)^6 = 1 + 12x + 60x^2 + 160x^3 + \cdots
Now multiply by (2−3x)(2 - 3x). The x3x^3 term comes from: 2(160x3)+(−3x)(60x2)=320x3−180x3=140x32(160x^3) + (-3x)(60x^2) = 320x^3 - 180x^3 = 140x^3 Thus, the coefficient of x3x^3 is 140140.
📝 Chapter Quiz
11

Kinematics

📌 Kinematics M1  ·  SUVAT equations  ·  Velocity–time graphs  ·  Calculus kinematics

Mechanics begins with motion in a straight line under constant acceleration.

▲ Reference — suvat equations

For constant acceleration: v=u+at v=u+at , s=ut+12at2 s=ut+\tfrac12 at^{2} , v2=u2+2as v^{2}=u^{2}+2as . Velocity is the derivative of displacement; acceleration the derivative of velocity.

Velocity
v=u+at v=u+at
Displacement
ut+12at2 ut+\tfrac12at^{2}
No time
v2=u2+2as v^{2}=u^{2}+2as
Acceleration
dvdt \tfrac{dv}{dt}
Coordinate plane; marked points (0, 0) (0, 0), (5, 20) (5, 20), (15, 20) (15, 20), (20, 0) (20, 0)-4-3-2-11234-4-224xy(0, 0)(5, 20)(15, 20)(20, 0)
Velocity–time trapezoid graph: uniform acceleration from 00 to 20 m/s20\text{ m/s} in 5 s5\text{ s}, constant velocity for 10 s10\text{ s}, and uniform deceleration to rest in 5 s5\text{ s}. Total displacement is the trapezoid area: 10+202×20=300 m\frac{10+20}{2} \times 20 = 300\text{ m}.
⚠ Common Traps & Exam Pitfalls
SUVAT vs Calculus: SUVAT formulas apply ONLY when acceleration is constant. If velocity or acceleration varies with time (e.g. v=3t2−12tv = 3t^2 - 12t), SUVAT yields zero marks — you must differentiate (a=dvdta = \frac{dv}{dt}) or integrate (s=∫v dts = \int v\,dt).

Velocity-Time graphs: Gradient equals acceleration (a=ΔvΔta = \frac{\Delta v}{\Delta t}). Total area under the graph equals displacement. For distance vs displacement: if the graph drops below the time axis (negative velocity), distance sums the absolute areas, whereas displacement nets them.

Vertical motion sign convention: Fix a reference direction at the start (usually upwards positive). Under this convention, acceleration is a=−g=−9.8 m/s2a = -g = -9.8\text{ m/s}^2 (or −9.81-9.81). Any position below the launch point corresponds to negative displacement s<0s < 0.
Worked example 11.A

With u=0 u=0 , a=2 a=2 , t=3 t=3 , find v v .

v=0+2(3)=6. v=0+2(3)=6.

Worked example — Calculus kinematics

A particle moves so that its velocity at time tt s is v=3t2−12t+9v=3t^2-12t+9 m/s. Find (a) the acceleration at t=2t=2, (b) when the particle is momentarily at rest.

(a) a=dvdt=6t−12a=\dfrac{dv}{dt}=6t-12. At t=2t=2: a=0a=0 m/s².

(b) v=0⇒3(t−1)(t−3)=0⇒t=1v=0\Rightarrow3(t-1)(t-3)=0\Rightarrow t=1 s or t=3t=3 s.

A train accelerates uniformly from rest to 30 m/s30\text{ m/s} in 20 s20\text{ s}, travels at constant speed 30 m/s30\text{ m/s} for 60 s60\text{ s}, and then decelerates uniformly to rest in 15 s15\text{ s}. Find: (a) the acceleration in the first phase, (b) the total distance travelled, (c) the average speed for the entire journey.
(a) a1=v−ut=30−020=1.5 m/s2a_1 = \dfrac{v - u}{t} = \dfrac{30 - 0}{20} = 1.5\text{ m/s}^2.
(b) Total distance is the area of the trapezoid on the vv-tt graph with parallel sides 60 s60\text{ s} and 20+60+15=95 s20 + 60 + 15 = 95\text{ s}, and height 30 m/s30\text{ m/s}: s=60+952×30=1552×30=155×15=2325 ms = \dfrac{60 + 95}{2} \times 30 = \dfrac{155}{2} \times 30 = 155 \times 15 = 2325\text{ m} (c) Average speed: Average speed=Total distanceTotal time=2325 m95 s≈24.47 m/s≈24.5 m/s (3 s.f.)\text{Average speed} = \dfrac{\text{Total distance}}{\text{Total time}} = \dfrac{2325\text{ m}}{95\text{ s}} \approx 24.47\text{ m/s} \approx 24.5\text{ m/s (3 s.f.)}
A stone is thrown vertically upwards with speed 15 m/s15\text{ m/s} from the top of a cliff 40 m40\text{ m} above sea level. Taking g=9.8 m/s2g = 9.8\text{ m/s}^2 and upwards as positive: (a) find the maximum height reached above the cliff, (b) calculate the time taken for the stone to reach the sea.
(a) At maximum height, v=0v = 0. u=+15 m/su = +15\text{ m/s}, a=−9.8 m/s2a = -9.8\text{ m/s}^2: v2=u2+2as⇒0=152+2(−9.8)s⇒19.6s=225⇒s=22519.6≈11.48 m≈11.5 mv^2 = u^2 + 2as \Rightarrow 0 = 15^2 + 2(-9.8)s \Rightarrow 19.6s = 225 \Rightarrow s = \dfrac{225}{19.6} \approx 11.48\text{ m} \approx 11.5\text{ m} (b) At the sea, the displacement relative to the launch point is s=−40 ms = -40\text{ m}. Use s=ut+12at2s = ut + \tfrac{1}{2}at^2: −40=15t+12(−9.8)t2⇒−40=15t−4.9t2⇒4.9t2−15t−40=0-40 = 15t + \tfrac{1}{2}(-9.8)t^2 \Rightarrow -40 = 15t - 4.9t^2 \Rightarrow 4.9t^2 - 15t - 40 = 0 Solve via quadratic formula: t=15±(−15)2−4(4.9)(−40)2(4.9)=15±225+7849.8=15±10099.8t = \dfrac{15 \pm \sqrt{(-15)^2 - 4(4.9)(-40)}}{2(4.9)} = \dfrac{15 \pm \sqrt{225 + 784}}{9.8} = \dfrac{15 \pm \sqrt{1009}}{9.8} Since 1009≈31.765\sqrt{1009} \approx 31.765, and t>0t > 0: t=15+31.7659.8=46.7659.8≈4.77 s (3 s.f.)t = \dfrac{15 + 31.765}{9.8} = \dfrac{46.765}{9.8} \approx 4.77\text{ s (3 s.f.)}
📝 Chapter Quiz
12

Forces & Equilibrium

📌 Forces & Equilibrium M1  ·  Resultant force  ·  Resolving into components  ·  Lami's theorem  ·  Friction F=μRF=\mu R

Types of Forces

Weight W=mgW=mg, Normal reaction NN, Tension TT, Friction F≤μNF\leq\mu N. Forces are vectors — resolve horizontally and vertically.

Equilibrium

A particle is in equilibrium when the resultant force is zero: ∑Fx=0\sum F_x=0 and ∑Fy=0\sum F_y=0. Use triangle/polygon of forces.

Resolving Forces

Force FF at angle θ\theta: horizontal component Fcos⁡θF\cos\theta, vertical component Fsin⁡θF\sin\theta.

Friction

Limiting friction: F=μNF=\mu N. When moving: F=μNF=\mu N. Static: F≤μNF\leq\mu N. μ\mu is the coefficient of friction.

Lami's Theorem

For three concurrent forces in equilibrium: F1sin⁡α=F2sin⁡β=F3sin⁡γ\dfrac{F_1}{\sin\alpha}=\dfrac{F_2}{\sin\beta}=\dfrac{F_3}{\sin\gamma}

Inclined Planes

On slope at angle α\alpha: component along slope =mgsin⁡α=mg\sin\alpha, perpendicular =mgcos⁡α=mg\cos\alpha.

▲ Forces & Equilibrium — Reference

A force is a vector (magnitude + direction). The resultant of forces is found by vector addition; for equilibrium the resultant is zero. Resolve forces into horizontal and vertical components: Fx=Fcos⁡θF_x=F\cos\theta, Fy=Fsin⁡θF_y=F\sin\theta. Friction force satisfies F≤μRF\leq\mu R; limiting equilibrium: F=μRF=\mu R.

Resolving
Fx=Fcos⁡θ,Fy=Fsin⁡θF_x=F\cos\theta,\quad F_y=F\sin\theta
Equilibrium
∑Fx=0&∑Fy=0\sum F_x=0\quad\&\quad\sum F_y=0
Friction (limiting)
F=μRF=\mu R
Resultant
R=Fx2+Fy2R=\sqrt{F_x^2+F_y^2}
Triangle with sides R = 16 N, W = 20 N, T = 12 N; right angle at vertex 1R = 16 NW = 20 NT = 12 N
Closed vector triangle of forces in equilibrium: Weight W=20 NW = 20\text{ N}, Tension TT, and Normal reaction RR summing to zero resultant.
⚠ Common Traps & Exam Pitfalls
Normal reaction is perpendicular to the plane: On an inclined plane of angle α\alpha, the normal reaction is R=mgcos⁡αR = mg\cos\alpha (if no other perpendicular forces act). Assuming R=mgR = mg on an inclined plane is an instant fatal error.

Gravity components on a slope: Gravity acts vertically downward. Its resolved components are mgsin⁡αmg\sin\alpha acting down the slope and mgcos⁡αmg\cos\alpha acting perpendicularly into the plane.

Friction is reactive: The friction force obeys F≤μRF \le \mu R. It only equals μR\mu R when motion is impending (limiting equilibrium) or actively occurring. If a system is stationary and not on the verge of slipping, FF balances whatever force opposes it, satisfying F<μRF < \mu R.
Worked example — Resolving forces in equilibrium

A particle is in equilibrium under three forces: 10 N acting due East, 8 N acting due North, and a third force FF. Find the magnitude and direction of FF.

For equilibrium: Fx=−10F_x=-10 N, Fy=−8F_y=-8 N.

∣F∣=100+64=164≈12.8 N,tan⁡θ=810⇒θ=38.7° W of S.|F|=\sqrt{100+64}=\sqrt{164}\approx12.8\text{ N},\quad\tan\theta=\frac{8}{10}\Rightarrow\theta=38.7°\text{ W of S}.

Worked example — Friction on an inclined plane

A block of mass 5 kg lies on a rough plane inclined at 30° to the horizontal (μ=0.4\mu=0.4, g=10g=10 m/s²). Find the friction force acting when the block is on the point of sliding down.

Normal reaction: R=5gcos⁡30°=50×32≈43.3R=5g\cos30°=50\times\tfrac{\sqrt3}{2}\approx43.3 N.

Friction (limiting, up the slope): F=0.4×43.3≈17.3F=0.4\times43.3\approx17.3 N.

Check: Gravity component down slope =50sin⁡30°=25=50\sin30°=25 N >F>F, so block would slide — friction acts up slope.

A block of mass 8 kg8\text{ kg} rests in limiting equilibrium on a rough plane inclined at 30∘30^\circ to the horizontal. Taking g=9.8 m/s2g = 9.8\text{ m/s}^2: (a) calculate the normal reaction RR, (b) find the coefficient of friction μ\mu between the block and the plane.
(a) Resolve perpendicular to the inclined plane: R=mgcos⁡30∘=8(9.8)cos⁡30∘=78.4×32=39.23≈67.9 N (3 s.f.)R = mg\cos 30^\circ = 8(9.8)\cos 30^\circ = 78.4 \times \dfrac{\sqrt{3}}{2} = 39.2\sqrt{3} \approx 67.9\text{ N (3 s.f.)} (b) Resolve parallel to the plane. Since the block is in limiting equilibrium on the verge of sliding down, friction F=μRF = \mu R acts up the plane: F=mgsin⁡30∘=8(9.8)sin⁡30∘=78.4×0.5=39.2 NF = mg\sin 30^\circ = 8(9.8)\sin 30^\circ = 78.4 \times 0.5 = 39.2\text{ N} Setting F=μRF = \mu R: μ=FR=mgsin⁡30∘mgcos⁡30∘=tan⁡30∘=13=33≈0.577 (3 s.f.)\mu = \dfrac{F}{R} = \dfrac{mg\sin 30^\circ}{mg\cos 30^\circ} = \tan 30^\circ = \dfrac{1}{\sqrt{3}} = \dfrac{\sqrt{3}}{3} \approx 0.577\text{ (3 s.f.)}
A small particle of weight 24 N24\text{ N} is held in equilibrium by two light inextensible strings. String AA makes an angle of 30∘30^\circ with the upward vertical, and string BB makes an angle of 60∘60^\circ with the upward vertical. Find the tensions TAT_A and TBT_B in the two strings.
Notice that the angle between string AA and string BB is 30∘+60∘=90∘30^\circ + 60^\circ = 90^\circ, so the strings are perpendicular.
Resolve horizontally: TAsin⁡30∘=TBsin⁡60∘⇒TA(0.5)=TB(32)⇒TA=3TBT_A\sin 30^\circ = T_B\sin 60^\circ \Rightarrow T_A(0.5) = T_B\left(\tfrac{\sqrt{3}}{2}\right) \Rightarrow T_A = \sqrt{3}T_B Resolve vertically: TAcos⁡30∘+TBcos⁡60∘=24⇒TA(32)+TB(0.5)=24T_A\cos 30^\circ + T_B\cos 60^\circ = 24 \Rightarrow T_A\left(\tfrac{\sqrt{3}}{2}\right) + T_B(0.5) = 24 Substitute TA=3TBT_A = \sqrt{3}T_B: (3TB)(32)+0.5TB=24⇒32TB+12TB=24⇒2TB=24⇒TB=12 N(\sqrt{3}T_B)\left(\tfrac{\sqrt{3}}{2}\right) + 0.5T_B = 24 \Rightarrow \tfrac{3}{2}T_B + \tfrac{1}{2}T_B = 24 \Rightarrow 2T_B = 24 \Rightarrow T_B = 12\text{ N} Then: TA=123≈20.8 N (3 s.f.)T_A = 12\sqrt{3} \approx 20.8\text{ N (3 s.f.)}
13

Newton's Laws of Motion

📌 Newton's Laws of Motion M1  ·  F=maF=ma  ·  Connected particles & pulleys  ·  Tension & reaction forces

Newton's First Law

A body remains at rest or in uniform motion unless acted upon by a resultant force. Inertia.

Newton's Second Law

F=maF=ma where FF is resultant force (N), mm is mass (kg), aa is acceleration (m/s²).

Newton's Third Law

For every action there is an equal and opposite reaction. Forces occur in equal pairs on different bodies.

Connected Particles

Particles connected by strings over pulleys: apply F=maF=ma to each particle separately, then solve simultaneously.

Acceleration on Slopes

Net force along slope =mgsin⁡α−Ffriction=mg\sin\alpha - F_{friction}. Apply F=maF=ma to find acceleration.

Momentum

Momentum p=mvp=mv. Newton's 2nd law: F=d(mv)dtF=\dfrac{d(mv)}{dt}. Conservation: m1u1+m2u2=m1v1+m2v2m_1u_1+m_2u_2=m_1v_1+m_2v_2.

▲ Newton's Laws — Reference

N1: A body remains at rest or in uniform motion unless acted on by a net force. N2: F=maF=ma (net force = mass × acceleration). N3: For every action there is an equal and opposite reaction. For connected particles (e.g. Atwood's machine), consider each particle separately; the tension TT is the same throughout an inextensible string over a smooth pulley.

Newton's 2nd Law
Fnet=maF_\text{net}=ma
Atwood's machine
a=(m1−m2)gm1+m2a=\dfrac{(m_1-m_2)g}{m_1+m_2}
Tension (same string)
Same TT throughout
Weight
W=mgW=mg
Coordinate plane; marked points (0, 0) (0, 0), (2 s, 4.9 m/s) (2, 4.9), (4 s, 9.8 m/s) (4, 9.8)-4-3-2-11234-4-224xy(0, 0)(2 s, 4.9 m/s)(4 s, 9.8 m/s)
Velocity–time graph of connected particles m1=5 kgm_1 = 5\text{ kg} and m2=3 kgm_2 = 3\text{ kg} accelerating at a=5−35+3(9.8)=2.45 m/s2a = \frac{5-3}{5+3}(9.8) = 2.45\text{ m/s}^2.
⚠ Common Traps & Exam Pitfalls
Separate equations for connected bodies: Never attempt to guess internal forces in one step. Always write ΣF=ma\Sigma F = ma separately for each particle in its direction of motion. Adding the equations cancels the internal tension TT and yields aa immediately.

Assumptions and vocabulary: Cambridge papers frequently ask for the physical significance of modeling assumptions: 'Light' means string/pulley mass is negligible; 'Inextensible' means accelerations of both particles have the same magnitude; 'Smooth' means tension TT is uniform across both sides.

Force exerted on the pulley: For two vertical hanging strings, the total downward force on the pulley is 2T2T. If one string is horizontal along a table and the other hangs vertically, the resultant force on the pulley is T2+T2=T2\sqrt{T^2 + T^2} = T\sqrt{2} at 45∘45^\circ.
Worked example — Single particle on a surface

A force of 30 N acts on a 6 kg box on a rough horizontal surface (μ=0.3\mu=0.3, g=10g=10 m/s²). Find the acceleration.

R=mg=60 N,Ffriction=0.3×60=18 N.R=mg=60\text{ N},\quad F_\text{friction}=0.3\times60=18\text{ N}.Fnet=30−18=12 N,a=126=2 m/s2.F_\text{net}=30-18=12\text{ N},\quad a=\frac{12}{6}=2\text{ m/s}^2.

Worked example — Connected particles over a pulley

Two particles of mass 4 kg and 6 kg are connected by a light inextensible string over a smooth pulley. Find the acceleration and the tension in the string (g=10g=10 m/s²).

Taking down as positive for the 6 kg particle:

6g−T=6a,T−4g=4a.6g-T=6a,\quad T-4g=4a.Adding: 2g=10a⇒a=2 m/s2,T=4(10+2)=48 N.\text{Adding: }2g=10a\Rightarrow a=2\text{ m/s}^2,\quad T=4(10+2)=48\text{ N}.

Two particles PP of mass 3 kg3\text{ kg} and QQ of mass 5 kg5\text{ kg} are connected by a light inextensible string passing over a smooth fixed pulley. The system is held at rest and released. Taking g=9.8 m/s2g = 9.8\text{ m/s}^2: (a) find the acceleration aa of the system, (b) calculate the tension TT in the string, (c) find the force exerted by the string on the pulley.
(a) Write F=maF = ma for each particle in its direction of motion:
For QQ (moving downwards): 5g−T=5a5g - T = 5a For PP (moving upwards): T−3g=3aT - 3g = 3a Add the equations: 2g=8a⇒a=2(9.8)8=2.45 m/s22g = 8a \Rightarrow a = \dfrac{2(9.8)}{8} = 2.45\text{ m/s}^2 (b) Substitute aa into the equation for PP: T=3g+3a=3(9.8+2.45)=3(12.25)=36.75 N≈36.8 NT = 3g + 3a = 3(9.8 + 2.45) = 3(12.25) = 36.75\text{ N} \approx 36.8\text{ N} (c) The pulley supports two vertical segments of string with tension TT, so the total downward force on the pulley is: Fpulley=2T=2(36.75)=73.5 NF_{\text{pulley}} = 2T = 2(36.75) = 73.5\text{ N}
A block of mass 4 kg4\text{ kg} is pulled along a rough horizontal plane (μ=0.25\mu = 0.25) by a pulling force of magnitude 25 N25\text{ N} acting at 30∘30^\circ above the horizontal. Taking g=9.8 m/s2g = 9.8\text{ m/s}^2: (a) show that the normal reaction R=26.7 NR = 26.7\text{ N}, (b) find the acceleration of the block.
(a) Resolve vertically (equilibrium in vertical direction): R+25sin⁡30∘=mg⇒R+25(0.5)=4(9.8)⇒R+12.5=39.2⇒R=26.7 NR + 25\sin 30^\circ = mg \Rightarrow R + 25(0.5) = 4(9.8) \Rightarrow R + 12.5 = 39.2 \Rightarrow R = 26.7\text{ N} (b) Limiting friction force opposes motion: F=μR=0.25×26.7=6.675 NF = \mu R = 0.25 \times 26.7 = 6.675\text{ N} Resolve horizontally using Fnet=maF_{\text{net}} = ma: 25cos⁡30∘−F=ma⇒25(32)−6.675=4a25\cos 30^\circ - F = ma \Rightarrow 25\left(\dfrac{\sqrt{3}}{2}\right) - 6.675 = 4a 21.651−6.675=4a⇒14.976=4a⇒a=14.9764≈3.74 m/s2 (3 s.f.)21.651 - 6.675 = 4a \Rightarrow 14.976 = 4a \Rightarrow a = \dfrac{14.976}{4} \approx 3.74\text{ m/s}^2\text{ (3 s.f.)}
14

Energy, Work & Power

📌 Energy, Work & Power M1  ·  Kinetic energy  ·  Gravitational PE  ·  Work-energy principle  ·  Power P=FvP=Fv

Work Done

W=Fdcos⁡θW=Fd\cos\theta where FF is force, dd distance, θ\theta angle between force and displacement. Units: Joules (J).

Kinetic Energy

KE=12mv2KE=\tfrac{1}{2}mv^2. Work-energy theorem: Wnet=ΔKE=12mv2−12mu2W_{net}=\Delta KE=\tfrac{1}{2}mv^2-\tfrac{1}{2}mu^2.

Potential Energy

Gravitational PE: GPE=mghGPE=mgh. Change in GPE: ΔGPE=mgΔh\Delta GPE=mg\Delta h.

Conservation of Energy

KE+PE=constantKE+PE=\text{constant} (no friction). With friction: ΔKE+ΔPE+Wfriction=0\Delta KE+\Delta PE+W_{friction}=0.

Power

P=Wt=FvP=\dfrac{W}{t}=Fv. Units: Watts (W). Maximum speed when driving force = resistance: P=Fresistance⋅vmaxP=F_{resistance}\cdot v_{max}.

Efficiency

efficiency=useful power outputpower input×100%\text{efficiency}=\dfrac{\text{useful power output}}{\text{power input}}\times100\%

▲ Energy, Work & Power — Reference

Kinetic energy: KE=12mv2\text{KE}=\tfrac{1}{2}mv^2. Gravitational PE: GPE=mgh\text{GPE}=mgh. Work-energy principle: net work done = change in KE. Work done by a force: W=Fdcos⁡θW=Fd\cos\theta. Power: P=Wt=FvP=\dfrac{W}{t}=Fv. Conservation of energy: KE1+GPE1=KE2+GPE2\text{KE}_1+\text{GPE}_1=\text{KE}_2+\text{GPE}_2 (no friction).

Kinetic energy
12mv2\tfrac{1}{2}mv^2
Gravitational PE
mghmgh
Work done
Fdcos⁡θFd\cos\theta
Power
P=FvP=Fv
Coordinate plane; marked points (0, 0) (0, 0), (5 m/s, 25 J) (5, 25), (10 m/s, 100 J) (10, 100)-4-3-2-11234-4-224xy(0, 0)(5 m/s, 25 J)(10 m/s, 100 J)
Quadratic relationship between kinetic energy and speed KE=12mv2KE = \frac{1}{2}mv^2 for a 2 kg2\text{ kg} mass. Doubling speed quadruples the kinetic energy.
⚠ Common Traps & Exam Pitfalls
Double-counting gravity: In energy equations, you either account for gravity through Gravitational Potential Energy (ΔKE+ΔPE=Wexternal\Delta KE + \Delta PE = W_{\text{external}}) OR through work done by gravity (ΔKE=Wg+Wfriction+…\Delta KE = W_g + W_{\text{friction}} + \dots). Including both simultaneously counts gravitational work twice.

Driving force vs Net force in P=FvP = Fv: The force in P=FvP = Fv is the tractive/driving force produced by the engine, NOT the resultant force. At maximum or steady velocity, acceleration is zero, so the driving force exactly equals the total opposing resistance (Fdrive=R+mgsin⁡αF_{\text{drive}} = R + mg\sin\alpha).

Work against friction: Work done against friction is W=F×dW = F \times d (where dd is the distance along the surface). This mechanical energy converts irreversibly into heat.
Worked example — Work-energy principle

A 2 kg ball rolls down a smooth slope of height 5 m from rest. Find its speed at the bottom (g=10g=10 m/s²).

Loss in GPE=Gain in KE:2×10×5=12×2×v2⇒v2=100⇒v=10 m/s.\text{Loss in GPE}=\text{Gain in KE}:\quad2\times10\times5=\tfrac{1}{2}\times2\times v^2\Rightarrow v^2=100\Rightarrow v=10\text{ m/s}.

Worked example — Power

A car of mass 900 kg moves at constant speed 30 m/s against a resistance of 500 N. Find the power output of the engine.

At constant speed, driving force = resistance = 500 N.

P=Fv=500×30=15 000 W=15 kW.P=Fv=500\times30=15\,000\text{ W}=15\text{ kW}.

A car of mass 1200 kg1200\text{ kg} ascends a hill of inclination α\alpha, where sin⁡α=120\sin\alpha = \tfrac{1}{20}, against a constant resistance to motion of 500 N500\text{ N}. Taking g=9.8 m/s2g = 9.8\text{ m/s}^2: (a) find the driving force required to travel at a steady speed of 25 m/s25\text{ m/s}, (b) calculate the power developed by the engine in kilowatts.
(a) Component of weight down the slope: W∥=mgsin⁡α=1200(9.8)(120)=60(9.8)=588 NW_{\parallel} = mg\sin\alpha = 1200(9.8)\left(\tfrac{1}{20}\right) = 60(9.8) = 588\text{ N} Since the car travels at steady speed (acceleration a=0a = 0), the engine driving force balances all resistance: Fdrive=Resistance+mgsin⁡α=500+588=1088 NF_{\text{drive}} = \text{Resistance} + mg\sin\alpha = 500 + 588 = 1088\text{ N} (b) Power output: P=Fdrive×v=1088×25=27 200 W=27.2 kWP = F_{\text{drive}} \times v = 1088 \times 25 = 27\,200\text{ W} = 27.2\text{ kW}
A block of mass 5 kg5\text{ kg} is released from rest at the top of a rough plane inclined at 30∘30^\circ to the horizontal. The length of the incline is 8 m8\text{ m} and the coefficient of friction is μ=0.2\mu = 0.2. Using the work-energy principle and taking g=9.8 m/s2g = 9.8\text{ m/s}^2, calculate the speed of the block at the bottom of the incline.
1. Vertical height descended: h=8sin⁡30∘=8(0.5)=4 mh = 8\sin 30^\circ = 8(0.5) = 4\text{ m}.
Initial gravitational potential energy: PE=mgh=5(9.8)(4)=196 J\text{PE} = mgh = 5(9.8)(4) = 196\text{ J} 2. Normal reaction: R=mgcos⁡30∘=5(9.8)(32)=24.53 NR = mg\cos 30^\circ = 5(9.8)\left(\tfrac{\sqrt{3}}{2}\right) = 24.5\sqrt{3}\text{ N}.
Friction force: F=μR=0.2(24.53)=4.93 NF = \mu R = 0.2(24.5\sqrt{3}) = 4.9\sqrt{3}\text{ N}.
Work done against friction over distance d=8 md = 8\text{ m}: Wfric=F×d=(4.93)×8=39.23≈67.896 JW_{\text{fric}} = F \times d = (4.9\sqrt{3}) \times 8 = 39.2\sqrt{3} \approx 67.896\text{ J} 3. By work-energy principle: Gain in KE=Loss in PE−Wfric⇒12mv2=196−67.896=128.104 J\text{Gain in KE} = \text{Loss in PE} - W_{\text{fric}} \Rightarrow \dfrac{1}{2}mv^2 = 196 - 67.896 = 128.104\text{ J} Substitute m=5 kgm = 5\text{ kg}: 2.5v2=128.104⇒v2=128.1042.5=51.2416⇒v=51.2416≈7.16 m/s (3 s.f.)2.5v^2 = 128.104 \Rightarrow v^2 = \dfrac{128.104}{2.5} = 51.2416 \Rightarrow v = \sqrt{51.2416} \approx 7.16\text{ m/s (3 s.f.)}
🔗 See also: Forces · Newton's Laws
15

Representation of Data

📌 Representation of Data S1  ·  Histograms & frequency density  ·  Cumulative frequency  ·  Mean, variance & SD  ·  Box-and-whisker plots

Stem-and-Leaf Diagrams

Display raw data in order. Back-to-back stem plots compare two datasets. Median and quartiles easy to read.

Box-and-Whisker Plots

Shows minimum, Q1, median, Q3, maximum. IQR = Q3 − Q1. Outliers: values outside Q1−1.5×IQRQ_1-1.5\times IQR or Q3+1.5×IQRQ_3+1.5\times IQR.

Histograms

Frequency density = frequency ÷ class width. Area of bar represents frequency. Used for continuous grouped data.

Cumulative Frequency

Ogive (cumulative frequency curve). Read median at n/2n/2, Q1 at n/4n/4, Q3 at 3n/43n/4.

Measures of Location

Mean xˉ=∑fx∑f\bar{x}=\dfrac{\sum fx}{\sum f}, Median (middle value), Mode (most frequent). For grouped data use midpoint.

Measures of Spread

Range, IQR, Variance σ2=∑fx2n−xˉ2\sigma^2=\dfrac{\sum fx^2}{n}-\bar{x}^2, Standard deviation σ\sigma.

▲ Representation of Data — Reference

For grouped data with nn values: mean xˉ=∑fx∑f\bar{x}=\dfrac{\sum fx}{\sum f}; variance σ2=∑fx2∑f−xˉ2\sigma^2=\dfrac{\sum fx^2}{\sum f}-\bar{x}^2; standard deviation σ=Var\sigma=\sqrt{\text{Var}}. In a histogram (unequal class widths), plot frequency density =freq/class width=\text{freq}/\text{class width}. In a cumulative frequency graph, the median is the n2\tfrac{n}{2}th value, Q1Q_1 is the n4\tfrac{n}{4}th, Q3Q_3 is the 3n4\tfrac{3n}{4}th.

Mean (grouped)
xˉ=∑fx∑f\bar{x}=\dfrac{\sum fx}{\sum f}
Variance
∑fx2∑f−xˉ2\dfrac{\sum fx^2}{\sum f}-\bar{x}^2
Freq. density
freq ÷ class width
IQR
Q3−Q1Q_3-Q_1
Distribution of Exam Test Scores — Box plot summary: Min 12, Q1 28, Median 44, Q3 62, Max 85Distribution of Exam Test Scores102030405060708090
Box-and-whisker plot displaying Five-Number Summary: Min = 12, Q1 = 28, Median = 44, Q3 = 62, Max = 85 with IQR = 34.
⚠ Common Traps & Exam Pitfalls
Histograms with unequal class widths: The vertical axis must ALWAYS represent frequency density (frequency÷class width\text{frequency} \div \text{class width}), never raw frequency. The area of each rectangle represents frequency.

Linear coding of data: If data values xx are transformed via y=ax+by = ax + b:
• Mean scales and shifts: yˉ=axˉ+b\bar{y} = a\bar{x} + b
• Variance scales by a2a^2 only: Var(y)=a2Var(x)\text{Var}(y) = a^2\text{Var}(x) (the additive constant bb does not affect spread)
• Standard deviation scales by ∣a∣|a|: σy=∣a∣σx\sigma_y = |a|\sigma_x.

Variance formula accuracy: When calculating σ2=∑x2n−xˉ2\sigma^2 = \frac{\sum x^2}{n} - \bar{x}^2, never round xˉ\bar{x} prematurely before squaring; keep exact fractions or high precision to avoid severe cancellation errors.
Worked example — Mean and variance from table

Scores: 1 (freq 2), 2 (freq 5), 3 (freq 8), 4 (freq 3), 5 (freq 2). Find the mean and standard deviation.

∑f=20\sum f=20, ∑fx=2+10+24+12+10=58\sum fx=2+10+24+12+10=58. Mean =58/20=2.9=58/20=2.9.

∑fx2=2+20+72+48+50=192\sum fx^2=2+20+72+48+50=192. Var =192/20−2.92=9.6−8.41=1.19=192/20-2.9^2=9.6-8.41=1.19. SD ≈1.09\approx1.09.

Worked example — Cumulative frequency

Data range 0–50. Cumulative frequencies at 10,20,30,40,50 are 5,18,34,44,50. Estimate the median and IQR.

Median at n/2=25n/2=25th value: read from cf graph at cf=25 → ≈27\approx27. Q1Q_1 at cf=12.5 → ≈18\approx18. Q3Q_3 at cf=37.5 → ≈33\approx33. IQR≈15\approx15.

A data set has mean 12 and standard deviation 4. A new value of 20 is added to n=9n=9 existing values. Without finding the new variance, find the new mean.
Old sum =9×12=108=9\times12=108. New sum =108+20=128=108+20=128. New mean =128/10=12.8=128/10=12.8.
A continuous dataset is grouped into class intervals. The interval 20≤x<3520 \le x < 35 has a frequency of 45. Find the frequency density for this class.
Class width w=35−20=15w = 35 - 20 = 15. Frequency density =frequencyclass width=4515=3.0= \frac{\text{frequency}}{\text{class width}} = \frac{45}{15} = 3.0. In a histogram, the height of the bar drawn on the interval [20,35)[20, 35) is 3.0.
16

Permutations & Combinations

📌 Permutations & Combinations S1  ·  Factorial  ·  nPr^nP_r  ·  nCr^nC_r  ·  Arrangements with identical items or restrictions

Factorial

n!=n×(n−1)×⋯×2×1n! = n\times(n-1)\times\cdots\times2\times1. Convention: 0!=10!=1.

Permutations

Ordered arrangements: nPr=n!(n−r)!^nP_r=\dfrac{n!}{(n-r)!}. Order matters. nn objects in a line: n!n! ways.

Combinations

Unordered selections: nCr=(nr)=n!r!(n−r)!^nC_r=\dbinom{n}{r}=\dfrac{n!}{r!(n-r)!}. Order does not matter.

Restrictions

Always together: treat as one unit, then (n−1)!×r!(n-1)!\times r!. Never together: total − (always together).

Circular Arrangements

(n−1)!(n-1)! ways to arrange nn objects in a circle (one position is fixed).

Identical Objects

Arrangements of nn objects with repeats: n!a! b! c!⋯\dfrac{n!}{a!\,b!\,c!\cdots}

▲ Permutations & Combinations — Reference

Permutation (order matters): nPr=n!(n−r)!^nP_r=\dfrac{n!}{(n-r)!}. Combination (order does not matter): nCr=(nr)=n!r! (n−r)!^nC_r=\dbinom{n}{r}=\dfrac{n!}{r!\,(n-r)!}. Arrangements with identical items: divide by the factorial of each repeated item. With restrictions: fix the restricted items first, then arrange the rest.

Permutation
nPr=n!(n−r)!^nP_r=\dfrac{n!}{(n-r)!}
Combination
nCr=n!r!(n−r)!^nC_r=\dfrac{n!}{r!(n-r)!}
Identical items
n!a! b!⋯\dfrac{n!}{a!\,b!\cdots}
Fix & arrange
Fix restricted → count rest
Bar chart: Values of 6Cr for r = 0 to 6 with categories: r=0 (1), r=1 (6), r=2 (15), r=3 (20), r=4 (15), r=5 (6), r=6 (1)05101520r=01r=16r=215r=320r=415r=56r=61Values of 6Cr for r = 0 to 6
Combinations (6r)\binom{6}{r} for r=0,1,…,6r = 0, 1, \ldots, 6, displaying the symmetric binomial coefficient distribution peaking at r=3r = 3.
⚠ Common Traps & Exam Pitfalls
Permutation vs Combination: If order or role matters (e.g. President and Vice President, line order, distinct positions), use permutations nPr^nP_r. If order does not matter (e.g. selecting a committee of 3 students), use combinations nCr^nC_r.

Identical items vs Distinct slots: Arranging nn objects where some are identical requires dividing by each repeat count: n!p! q!⋯\frac{n!}{p!\,q!\cdots}.

'Together' vs 'Separated': For items that must stay together, glue them as a single super-element and arrange (n−k+1)!(n - k + 1)!, then multiply by k!k! for internal order. For items that must NEVER be adjacent, arrange the unrestricted items first, creating slots ‾⋆‾⋆…\underline{\quad}\star\underline{\quad}\star\dots, and choose slot positions.
Worked example — Combinations with restrictions

A committee of 4 is chosen from 5 men and 6 women. Find the number of ways if the committee must contain at least 2 women.

Exactly 2W: (62)(52)=15×10=150\binom{6}{2}\binom{5}{2}=15\times10=150. Exactly 3W: (63)(51)=20×5=100\binom{6}{3}\binom{5}{1}=20\times5=100. Exactly 4W: (64)(50)=15\binom{6}{4}\binom{5}{0}=15. Total: 265265.

Worked example — Arrangements of letters

How many different arrangements are there of the letters of the word BANANA?

6 letters; N appears 2 times, A appears 3 times: 6!3! 2!=72012=60\dfrac{6!}{3!\,2!}=\dfrac{720}{12}=60.

In how many ways can 5 people be seated in a row if two particular people (A and B) must not sit next to each other?
Total =5!=120=5!=120. Cases where A & B are adjacent: treat AB as a block → 4!×2=484!\times2=48. Answer: 120−48=72120-48=72.
Find the number of ways to arrange the 7 letters in the word SUCCESS.
The word SUCCESS has 7 letters with 3 S's, 2 C's, 1 U, and 1 E. The number of distinct permutations is 7!3! 2!=50406×2=504012=420\frac{7!}{3!\,2!} = \frac{5040}{6 \times 2} = \frac{5040}{12} = 420.
🔗 See also: Binomial Distribution
17

Discrete Random Variables

📌 Discrete Random Variables S1  ·  Probability distribution table  ·  E(X)E(X)  ·  Var(X)\text{Var}(X)  ·  Linear transforms E(aX+b)E(aX+b)

Probability Distribution

Table of xx values and corresponding P(X=x)P(X=x). Must satisfy: ∑P(X=x)=1\sum P(X=x)=1 and P(X=x)≥0P(X=x)\geq0.

Expectation

E(X)=∑x⋅P(X=x)=μE(X)=\sum x\cdot P(X=x)=\mu. Also E(aX+b)=aE(X)+bE(aX+b)=aE(X)+b.

Variance

Var(X)=E(X2)−[E(X)]2\text{Var}(X)=E(X^2)-[E(X)]^2 where E(X2)=∑x2P(X=x)E(X^2)=\sum x^2P(X=x). Also Var(aX+b)=a2Var(X)\text{Var}(aX+b)=a^2\text{Var}(X).

Standard Deviation

σ=Var(X)\sigma=\sqrt{\text{Var}(X)}. Measures spread around the mean.

Uniform Distribution

Each value equally likely. If XX takes values 1,2,…,n1,2,\ldots,n: E(X)=n+12E(X)=\dfrac{n+1}{2}, Var(X)=n2−112\text{Var}(X)=\dfrac{n^2-1}{12}.

Combined Variables

E(X+Y)=E(X)+E(Y)E(X+Y)=E(X)+E(Y). If independent: Var(X+Y)=Var(X)+Var(Y)\text{Var}(X+Y)=\text{Var}(X)+\text{Var}(Y).

▲ Discrete Random Variables — Reference

A discrete random variable XX has a probability distribution with ∑P(X=x)=1\sum P(X=x)=1. Expectation: E(X)=∑x P(X=x)E(X)=\sum x\,P(X=x). Variance: Var(X)=E(X2)−[E(X)]2\text{Var}(X)=E(X^2)-[E(X)]^2 where E(X2)=∑x2P(X=x)E(X^2)=\sum x^2 P(X=x). For linear transforms: E(aX+b)=aE(X)+bE(aX+b)=aE(X)+b; Var(aX+b)=a2Var(X)\text{Var}(aX+b)=a^2\text{Var}(X).

E(X)
∑x P(X=x)\sum x\,P(X=x)
Var(X)
E(X2)−[E(X)]2E(X^2)-[E(X)]^2
E(aX+b)
aE(X)+baE(X)+b
Var(aX+b)
a2Var(X)a^2\text{Var}(X)
Bar chart: Discrete PMF P(X = x) with categories: x=1 (10), x=2 (30), x=3 (40), x=4 (20)010203040x=110x=230x=340x=420Discrete PMF P(X = x)
Probability distribution of a discrete random variable XX taking values {1,2,3,4}\{1, 2, 3, 4\} with ∑P(X=x)=1.0\sum P(X=x) = 1.0.
⚠ Common Traps & Exam Pitfalls
Variance formula trap: Remember Var(X)=E(X2)−[E(X)]2\text{Var}(X) = E(X^2) - [E(X)]^2. Do not forget to square E(X)E(X), and do not compute E(X2)−E(X)E(X^2) - E(X).

Linear coding of variance: Var(aX+b)=a2Var(X)\text{Var}(aX + b) = a^2 \text{Var}(X). Notice that the constant bb is eliminated completely, and a negative multiplier aa becomes positive due to squaring (e.g. Var(5−2X)=(−2)2Var(X)=4Var(X)\text{Var}(5 - 2X) = (-2)^2 \text{Var}(X) = 4\text{Var}(X)).

Sum of probabilities: The total probability MUST sum to 1: ∑P(X=x)=1\sum P(X = x) = 1. Always verify this condition first when solving for unknown parameters pp or kk.
Worked example — Finding E(X) and Var(X)

A biased die shows: P(1)=0.1,P(2)=0.2,P(3)=0.3,P(4)=0.3,P(5)=0.1P(1)=0.1,P(2)=0.2,P(3)=0.3,P(4)=0.3,P(5)=0.1. Find E(X)E(X) and Var(X)\text{Var}(X).

E(X)=0.1(1)+0.2(2)+0.3(3)+0.3(4)+0.1(5)=0.1+0.4+0.9+1.2+0.5=3.1.E(X)=0.1(1)+0.2(2)+0.3(3)+0.3(4)+0.1(5)=0.1+0.4+0.9+1.2+0.5=3.1.E(X2)=0.1(1)+0.2(4)+0.3(9)+0.3(16)+0.1(25)=0.1+0.8+2.7+4.8+2.5=10.9.E(X^2)=0.1(1)+0.2(4)+0.3(9)+0.3(16)+0.1(25)=0.1+0.8+2.7+4.8+2.5=10.9.Var(X)=10.9−3.12=10.9−9.61=1.29.\text{Var}(X)=10.9-3.1^2=10.9-9.61=1.29.

Worked example — Unknown probability

XX takes values 0, 1, 2 with P(X=0)=kP(X=0)=k, P(X=1)=2kP(X=1)=2k, P(X=2)=3kP(X=2)=3k. Find kk and E(X)E(X).

k+2k+3k=1⇒k=16.E(X)=0⋅16+1⋅26+2⋅36=86=43.k+2k+3k=1\Rightarrow k=\tfrac{1}{6}.\quad E(X)=0\cdot\tfrac{1}{6}+1\cdot\tfrac{2}{6}+2\cdot\tfrac{3}{6}=\tfrac{8}{6}=\tfrac{4}{3}.

E(X)=3E(X)=3 and Var(X)=2\text{Var}(X)=2. Find E(3X−1)E(3X-1) and Var(3X−1)\text{Var}(3X-1).
E(3X−1)=3(3)−1=8E(3X-1)=3(3)-1=8. Var(3X−1)=9×2=18\text{Var}(3X-1)=9\times2=18.
A discrete random variable YY has E(Y)=5E(Y) = 5 and Var(Y)=4\text{Var}(Y) = 4. Calculate E(Y2)E(Y^2) and Var(10−3Y)\text{Var}(10 - 3Y).
Using Var(Y)=E(Y2)−[E(Y)]2\text{Var}(Y) = E(Y^2) - [E(Y)]^2, we get E(Y2)=Var(Y)+[E(Y)]2=4+52=4+25=29E(Y^2) = \text{Var}(Y) + [E(Y)]^2 = 4 + 5^2 = 4 + 25 = 29. For the linear transformation: Var(10−3Y)=(−3)2Var(Y)=9×4=36\text{Var}(10 - 3Y) = (-3)^2 \text{Var}(Y) = 9 \times 4 = 36.
18

Binomial Distribution

📌 Binomial Distribution S1  ·  X∼B(n,p)X\sim B(n,p)  ·  P(X=r)=(nr)pr(1−p)n−rP(X=r)=\binom{n}{r}p^r(1-p)^{n-r}  ·  Mean npnp  ·  Variance np(1−p)np(1-p)

Conditions

Fixed number of trials nn; each trial has two outcomes (success/failure); constant probability pp; trials independent. Then X∼B(n,p)X\sim B(n,p).

Probability Formula

P(X=r)=(nr)pr(1−p)n−rP(X=r)=\dbinom{n}{r}p^r(1-p)^{n-r} for r=0,1,2,…,nr=0,1,2,\ldots,n.

Mean and Variance

E(X)=npE(X)=np, Var(X)=np(1−p)\text{Var}(X)=np(1-p), σ=np(1−p)\sigma=\sqrt{np(1-p)}.

Cumulative Probabilities

Use tables or calculator: P(X≤r)P(X\leq r). Note: P(X≥r)=1−P(X≤r−1)P(X\geq r)=1-P(X\leq r-1).

Normal Approximation

If nn large and pp close to 0.5: X≈N(np, np(1−p))X\approx N(np,\,np(1-p)) with continuity correction.

Finding Unknown n or p

Set up equations using given probabilities and solve. May require trial and error or logarithms for nn.

▲ Binomial Distribution — Reference

If X∼B(n,p)X\sim B(n,p): nn independent trials, each with probability pp of success. P(X=r)=(nr)pr(1−p)n−rP(X=r)=\dbinom{n}{r}p^r(1-p)^{n-r}. Mean: E(X)=npE(X)=np. Variance: Var(X)=np(1−p)\text{Var}(X)=np(1-p). Use the binomial distribution when: fixed nn, trials independent, constant pp, only 2 outcomes (success/failure).

P(X=r)P(X=r)
(nr)pr(1−p)n−r\binom{n}{r}p^r(1-p)^{n-r}
Mean
npnp
Variance
np(1−p)np(1-p)
Conditions
Fixed nn, independent, constant pp
Bar chart: Binomial Distribution B(5, 0.4) with categories: r=0 (8), r=1 (26), r=2 (35), r=3 (23), r=4 (8), r=5 (1)09182635r=08r=126r=235r=323r=48r=51Binomial Distribution B(5, 0.4)
Binomial distribution X∼B(5,0.4)X \sim B(5, 0.4) probability distribution across r=0,1,2,3,4,5r = 0, 1, 2, 3, 4, 5.
⚠ Common Traps & Exam Pitfalls
Inequality bounds for discrete distributions: Unlike continuous variables, strict inequalities make a critical difference:
• P(X≥r)=1−P(X≤r−1)P(X \ge r) = 1 - P(X \le r - 1) (NOT 1−P(X≤r)1 - P(X \le r))
• P(X>r)=1−P(X≤r)P(X > r) = 1 - P(X \le r)
• P(X<r)=P(X≤r−1)P(X < r) = P(X \le r - 1).

'At least one' complement shortcut: P(X≥1)=1−P(X=0)=1−(1−p)nP(X \ge 1) = 1 - P(X = 0) = 1 - (1-p)^n. Always look for this time-saving identity in exam questions.

Four binomial conditions: Cambridge exam questions frequently ask you to state assumptions justifying the binomial model: (1) Fixed number of trials nn, (2) Constant probability of success pp, (3) Independent trials, (4) Exactly two mutually exclusive outcomes (success/failure).
Worked example — Exact probability

X∼B(8,0.3)X\sim B(8,0.3). Find (a) P(X=3)P(X=3), (b) P(X≤1)P(X\leq1).

(a) P(X=3)=(83)(0.3)3(0.7)5=56×0.027×0.16807≈0.2541P(X=3)=\binom{8}{3}(0.3)^3(0.7)^5=56\times0.027\times0.16807\approx0.2541.

(b) P(X=0)=(0.7)8≈0.0576P(X=0)=(0.7)^8\approx0.0576; P(X=1)=8(0.3)(0.7)7≈0.1977P(X=1)=8(0.3)(0.7)^7\approx0.1977. P(X≤1)≈0.2553P(X\leq1)\approx0.2553.

Worked example — Finding n from mean

The mean of X∼B(n,0.4)X\sim B(n,0.4) is 6. Find nn and the standard deviation.

np=6⇒n=15.σ=15×0.4×0.6=3.6≈1.90.np=6\Rightarrow n=15.\quad\sigma=\sqrt{15\times0.4\times0.6}=\sqrt{3.6}\approx1.90.

A fair coin is tossed 10 times. Find the probability of getting (a) exactly 6 heads, (b) fewer than 3 heads.
(a) (106)(0.5)10=210×11024≈0.2051\binom{10}{6}(0.5)^{10}=210\times\tfrac{1}{1024}\approx0.2051. (b) P(X≤2)=P(0)+P(1)+P(2)=1+10+451024=561024≈0.0547P(X\leq2)=P(0)+P(1)+P(2)=\tfrac{1+10+45}{1024}=\tfrac{56}{1024}\approx0.0547.
In a manufacturing batch, 5% of components are defective. A sample of 12 components is inspected. Find the probability that at least 2 components are defective.
Let X∼B(12,0.05)X \sim B(12, 0.05). We need P(X≥2)=1−[P(X=0)+P(X=1)]P(X \ge 2) = 1 - [P(X = 0) + P(X = 1)]. P(X=0)=(0.95)12≈0.5404P(X = 0) = (0.95)^{12} \approx 0.5404. P(X=1)=12(0.05)(0.95)11≈0.3413P(X = 1) = 12(0.05)(0.95)^{11} \approx 0.3413. Thus, P(X≥2)=1−(0.5404+0.3413)=1−0.8817=0.118P(X \ge 2) = 1 - (0.5404 + 0.3413) = 1 - 0.8817 = 0.118 (3 s.f.).
19

Normal Distribution

📌 Normal Distribution S1  ·  X∼N(μ,σ2)X\sim N(\mu,\sigma^2)  ·  Standardising Z=X−μσZ=\tfrac{X-\mu}{\sigma}  ·  Tables & symmetry  ·  Finding μ\mu or σ\sigma

The Normal Curve

Bell-shaped, symmetric about mean μ\mu. X∼N(μ,σ2)X\sim N(\mu,\sigma^2). Approximately 68%/95%/99.7% within 1/2/3 standard deviations.

Standardising

Z=X−μσ∼N(0,1)Z=\dfrac{X-\mu}{\sigma}\sim N(0,1). Use ZZ-tables (standard normal) to find probabilities.

Finding Probabilities

P(X<a)=Φ ⁣(a−μσ)P(X<a)=\Phi\!\left(\dfrac{a-\mu}{\sigma}\right). Use symmetry: P(Z<−z)=1−P(Z<z)P(Z<-z)=1-P(Z<z).

Inverse Normal

Given probability, find the value. P(X<a)=p⇒a=μ+zσP(X<a)=p\Rightarrow a=\mu+z\sigma where z=Φ−1(p)z=\Phi^{-1}(p).

Finding μ or σ

Set up two equations from given probabilities, solve simultaneously for unknown parameters.

Normal Approximation

To Binomial B(n,p)B(n,p): if nn large, np>5np>5, n(1−p)>5n(1-p)>5: use N(np,np(1−p))N(np,np(1-p)) with continuity correction ±0.5\pm0.5.

▲ Normal Distribution — Reference

If X∼N(μ,σ2)X\sim N(\mu,\sigma^2): standardise with Z=X−μσZ=\dfrac{X-\mu}{\sigma} where Z∼N(0,1)Z\sim N(0,1). Use tables (or calculator) for Φ(z)=P(Z≤z)\Phi(z)=P(Z\leq z). Key symmetry: P(Z≤−z)=1−P(Z≤z)P(Z\leq -z)=1-P(Z\leq z). For inverse normal: given a probability, find the corresponding xx value using x=μ+zσx=\mu+z\sigma.

Standardise
Z=X−μσZ=\dfrac{X-\mu}{\sigma}
Symmetry
P(Z≤−z)=1−Φ(z)P(Z\leq-z)=1-\Phi(z)
Inverse normal
x=μ+zσx=\mu+z\sigma
Normal approx to B
Use when nn large, p≈0.5p\approx0.5
Normal distribution bell curve (mean 0, sd 1): Standard Normal Distribution N(0,1) showing shaded probability regionStandard Normal Distribution N(0,1)-3σ-2σ-1σ0+1σ+2σ+3σ
Standard normal distribution curve Z∼N(0,1)Z \sim N(0, 1) with shaded region representing P(−1.5≤Z≤1.5)≈0.8664P(-1.5 \le Z \le 1.5) \approx 0.8664.
⚠ Common Traps & Exam Pitfalls
Variance vs Standard Deviation: Cambridge notation specifies X∼N(μ,σ2)X \sim N(\mu, \sigma^2). When standardising Z=X−μσZ = \frac{X - \mu}{\sigma}, remember to divide by σ=σ2\sigma = \sqrt{\sigma^2}, NOT by σ2\sigma^2.

Negative z-values and tables: Standard normal tables provide Φ(z)\Phi(z) only for z>0z > 0. By symmetry: Φ(−z)=1−Φ(z)\Phi(-z) = 1 - \Phi(z). For lower-tail probabilities P(Z<−1.25)=1−Φ(1.25)P(Z < -1.25) = 1 - \Phi(1.25).

Continuity correction (Normal approx to Binomial): When approximating discrete X∼B(n,p)X \sim B(n, p) by continuous Y∼N(np,np(1−p))Y \sim N(np, np(1-p)):
• P(X≥a)→P(Y>a−0.5)P(X \ge a) \to P(Y > a - 0.5)
• P(X>a)→P(Y>a+0.5)P(X > a) \to P(Y > a + 0.5)
• P(X≤a)→P(Y<a+0.5)P(X \le a) \to P(Y < a + 0.5)
• P(X=a)→P(a−0.5<Y<a+0.5)P(X = a) \to P(a - 0.5 < Y < a + 0.5).
Worked example — Finding a probability

X∼N(50,16)X\sim N(50,16) so σ=4\sigma=4. Find P(44≤X≤58)P(44\leq X\leq58).

P ⁣(44−504≤Z≤58−504)=P(−1.5≤Z≤2)=Φ(2)−Φ(−1.5).P\!\left(\frac{44-50}{4}\leq Z\leq\frac{58-50}{4}\right)=P(-1.5\leq Z\leq 2)=\Phi(2)-\Phi(-1.5).=0.9772−(1−0.9332)=0.9772−0.0668=0.9104.=0.9772-(1-0.9332)=0.9772-0.0668=0.9104.

Worked example — Finding μ\mu

X∼N(μ,25)X\sim N(\mu,25). Given P(X>43)=0.2119P(X>43)=0.2119, find μ\mu.

P(Z>43−μ5)=0.2119⇒43−μ5=0.8P(Z>\tfrac{43-\mu}{5})=0.2119\Rightarrow\tfrac{43-\mu}{5}=0.8 (from tables). μ=43−4=39\mu=43-4=39.

X∼N(30,σ2)X\sim N(30,\sigma^2) and P(X<25)=0.0668P(X<25)=0.0668. Find σ\sigma.
P(Z<25−30σ)=0.0668⇒−5σ=−1.5⇒σ=51.5≈3.33P(Z<\tfrac{25-30}{\sigma})=0.0668\Rightarrow\tfrac{-5}{\sigma}=-1.5\Rightarrow\sigma=\tfrac{5}{1.5}\approx3.33.
The random variable X∼N(μ,σ2)X \sim N(\mu, \sigma^2) satisfies P(X<65)=0.8413P(X < 65) = 0.8413 and P(X<45)=0.0228P(X < 45) = 0.0228. Find the values of μ\mu and σ\sigma.
Standardising: Φ(65−μσ)=0.8413⇒65−μσ=1.0\Phi\left(\frac{65 - \mu}{\sigma}\right) = 0.8413 \Rightarrow \frac{65 - \mu}{\sigma} = 1.0, so 65−μ=σ65 - \mu = \sigma.
For the lower tail: P(X<45)=0.0228⇒Φ(45−μσ)=0.0228⇒45−μσ=−2.0P(X < 45) = 0.0228 \Rightarrow \Phi\left(\frac{45 - \mu}{\sigma}\right) = 0.0228 \Rightarrow \frac{45 - \mu}{\sigma} = -2.0, so μ−45=2σ\mu - 45 = 2\sigma.
Adding the two equations: 65−45=3σ⇒20=3σ⇒σ=6.6765 - 45 = 3\sigma \Rightarrow 20 = 3\sigma \Rightarrow \sigma = 6.67. Then μ=65−6.67=58.33\mu = 65 - 6.67 = 58.33.
§

Practice set

Fifty AS-style problems across the Pure core plus statistics, tagged by difficulty. Click any problem for a full worked solution.

1

Simplify x3⋅x4 x^{3}\cdot x^{4} .

Basic
x7. x^{7}.
2

Evaluate 2−3 2^{-3} .

Intermediate
123=18. \frac{1}{2^{3}}=\tfrac{1}{8}.
3

Simplify 12 \sqrt{12} .

Intermediate
4⋅3=23. \sqrt{4\cdot3}=2\sqrt{3}.
4

Rationalise 12 \dfrac{1}{\sqrt{2}} .

Advanced

Multiply by 22 \tfrac{\sqrt2}{\sqrt2} :

22. \tfrac{\sqrt{2}}{2}.
5

Simplify (x2)5 (x^{2})^{5} .

Intermediate
x10. x^{10}.
6

Evaluate 271/3 27^{1/3} .

Advanced
273=3. \sqrt[3]{27}=3.
7

Solve x2=16 x^{2}=16 .

Basic
x=±4. x=\pm4.
8

Factor x2+5x+6 x^{2}+5x+6 .

Intermediate
(x+2)(x+3). (x+2)(x+3).
9

Solve x2−6x+8=0 x^{2}-6x+8=0 .

Intermediate

(x−2)(x−4)=0 (x-2)(x-4)=0 :

x=2, 4. x=2,\ 4.
10

Complete the square for x2+4x x^{2}+4x .

Intermediate
(x+2)2−4. (x+2)^{2}-4.
11

How many real roots does x2+x+1=0 x^{2}+x+1=0 have?

Advanced

Discriminant =1−4=−3<0 =1-4=-3<0 :

none. \text{none.}
12

Find the sum of the roots of x2−5x+6=0 x^{2}-5x+6=0 .

Intermediate
2+3=5. 2+3=5.
13

Solve 2x2−5x−3=0 2x^{2}-5x-3=0 .

Advanced

(2x+1)(x−3)=0 (2x+1)(x-3)=0 :

x=3, −12. x=3,\ -\tfrac12.
14

Find the vertex of y=x2−4x+3 y=x^{2}-4x+3 .

Intermediate

(x−2)2−1 (x-2)^{2}-1 :

(2, −1). (2,\,-1).
15

Solve x+y=5 x+y=5 , x−y=1 x-y=1 .

Intermediate

Add: 2x=6 2x=6 :

x=3, y=2. x=3,\ y=2.
16

Solve 2x+y=8 2x+y=8 , y=x−1 y=x-1 .

Intermediate

2x+x−1=8⇒x=3 2x+x-1=8 \Rightarrow x=3 :

x=3, y=2. x=3,\ y=2.
17

Solve y=x2 y=x^{2} , y=x+2 y=x+2 .

Advanced

x2−x−2=0⇒(x−2)(x+1)=0 x^{2}-x-2=0\Rightarrow(x-2)(x+1)=0 :

(2,4), (−1,1). (2,4),\ (-1,1).
18

Solve 2x−3>5 2x-3>5 .

Intermediate

2x>8 2x>8 :

x>4. x>4.
19

Solve 3x+1≤10 3x+1\le10 .

Intermediate

3x≤9 3x\le9 :

x≤3. x\le3.
20

Solve x2−4<0 x^{2}-4<0 .

Advanced
−2<x<2. -2<x<2.
21

Find the gradient through (1,2) (1,2) and (4,11) (4,11) .

Intermediate
11−24−1=3. \frac{11-2}{4-1}=3.
22

Find the midpoint of (2,3) (2,3) and (8,7) (8,7) .

Intermediate
(5, 5). (5,\,5).
23

Find the equation of the line with gradient 2 2 through (1,3) (1,3) .

Advanced

y−3=2(x−1) y-3=2(x-1) :

y=2x+1. y=2x+1.
24

Find the distance between (1,1) (1,1) and (4,5) (4,5) .

Intermediate
9+16=5. \sqrt{9+16}=5.
25

State the centre of (x−2)2+(y+3)2=25 (x-2)^{2}+(y+3)^{2}=25 .

Advanced
(2, −3). (2,\,-3).
26

State the radius of x2+y2=49 x^{2}+y^{2}=49 .

Intermediate
r=7. r=7.
27

Describe y=x2+3 y=x^{2}+3 relative to y=x2 y=x^{2} .

Intermediate

A translation 3 3 units up.

28

Describe y=(x−2)2 y=(x-2)^{2} relative to y=x2 y=x^{2} .

Intermediate

A translation 2 2 units to the right.

29

Describe y=−x2 y=-x^{2} relative to y=x2 y=x^{2} .

Advanced

A reflection in the x x -axis.

30

How does y=f(x)+k y=f(x)+k transform the graph of y=f(x) y=f(x) ?

Intermediate

A vertical translation by k k .

31

Evaluate sin⁡30∘ \sin30^{\circ} .

Intermediate
12. \tfrac12.
32

Evaluate cos⁡0∘ \cos0^{\circ} .

Intermediate
1. 1.
33

Evaluate tan⁡45∘ \tan45^{\circ} .

Intermediate
1. 1.
34

Solve sin⁡θ=12 \sin\theta=\tfrac12 for 0∘≤θ≤180∘ 0^{\circ}\le\theta\le180^{\circ} .

Advanced
θ=30∘, 150∘. \theta=30^{\circ},\ 150^{\circ}.
35

Simplify sin⁡2θ+cos⁡2θ \sin^{2}\theta+\cos^{2}\theta .

Intermediate
1. 1.
36

State the exact value of sin⁡60∘ \sin60^{\circ} .

Advanced
32. \tfrac{\sqrt{3}}{2}.
37

Evaluate cos⁡90∘ \cos90^{\circ} .

Intermediate
0. 0.
38

State the period of y=sin⁡x y=\sin x .

Advanced
360∘. 360^{\circ}.
39

Differentiate x2 x^{2} .

Intermediate
2x. 2x.
40

Differentiate x3 x^{3} .

Intermediate
3x2. 3x^{2}.
41

Differentiate 5x 5x .

Intermediate
5. 5.
42

Find dydx \dfrac{dy}{dx} for y=x2+3x y=x^{2}+3x .

Advanced
2x+3. 2x+3.
43

Find ∫2x dx \displaystyle\int 2x\,dx .

Intermediate
x2+C. x^{2}+C.
44

Find ∫x2 dx \displaystyle\int x^{2}\,dx .

Advanced
x33+C. \tfrac{x^{3}}{3}+C.
45

Find the gradient of y=x2 y=x^{2} at x=3 x=3 .

Intermediate

dydx=2x=6 \tfrac{dy}{dx}=2x=6 :

6. 6.
46

Evaluate ∫012x dx \displaystyle\int_{0}^{1} 2x\,dx .

Advanced
[x2]01=1. \left[x^{2}\right]_{0}^{1}=1.
47

Find the mean of 2, 4, 6, 8 2,\,4,\,6,\,8 .

Intermediate
204=5. \frac{20}{4}=5.
48

Find the median of 3, 7, 9, 12, 20 3,\,7,\,9,\,12,\,20 .

Intermediate
9. 9.
49

A fair die is rolled. Find P(even) P(\text{even}) .

Advanced
36=12. \tfrac{3}{6}=\tfrac12.
50

Find the range of 5, 9, 2, 11 5,\,9,\,2,\,11 .

Intermediate
11−2=9. 11-2=9.
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Based on Cambridge International AS Level Mathematics 9709 Paper 1: Pure Mathematics 1. Structured questions (1 hr 50 min, 75 marks) covering quadratics, functions, coordinate geometry, circular measure, trigonometry, series, differentiation and integration.

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