Functions & Their Graphs
📌 Functions & Their Graphs A2 · Composition · Inverse · Domain & range · Piecewise functions
Algebra 2 is really the study of functions as objects you can combine, invert and transform. Fluency with notation, domain and range underpins every later chapter.
A function assigns to each input exactly one output. We write \( y=f(x) \); the set of allowed inputs is the domain and the set of resulting outputs is the range.
Given \( f(x)=2x+1 \) and \( g(x)=x^{2} \), find \( f\big(g(2)\big) \). Work inside-out: \( g(2)=4 \), then \( f(4)=2(4)+1 \):
Find the inverse of \( f(x)=2x-6 \). Write \( y=2x-6 \), swap and solve: \( x=2y-6 \Rightarrow y=\tfrac{x+6}{2} \):
Quadratics & Complex Numbers
📌 Quadratics & Complex Numbers A2 · Completing the square · Discriminant · Complex roots \(a\pm bi\)
Every quadratic can be solved — and when the discriminant is negative, the solutions live in the complex numbers. This chapter ties graphing, factoring and the imaginary unit together.
Define \( i=\sqrt{-1} \), so \( i^{2}=-1 \). A complex number has the form \( a+bi \) with \( a,b \) real; add and multiply just as with binomials, replacing \( i^{2} \) by \( -1 \).
Describe the roots of \( x^{2}+2x+5=0 \). Discriminant \( \Delta=2^{2}-4(1)(5)=-16<0 \), so there are no real roots — two complex conjugates. Solving:
Multiply \( (2+i)(3-i) \).
Polynomial Functions
📌 Polynomial Functions A2 · Factor theorem · Remainder theorem · Rational roots · End behaviour
Beyond quadratics lie cubics, quartics and higher. Two questions dominate: where are the zeros, and what does the graph do at its ends? The leading term answers the second on its own.
The end behaviour of a polynomial is governed entirely by its leading term \( a x^{n} \): the sign of \( a \) and the parity of \( n \). And \( (x-r) \) is a factor exactly when \( r \) is a zero (\( f(r)=0 \)).
Change the degree and the leading coefficient below. Watch how the arms of the graph flip with the sign of \( a \), and how an even degree sends both arms the same way while an odd degree sends them opposite ways.
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Find the zeros of \( f(x)=x^{3}-9x \). Factor out \( x \), then a difference of squares:
Find the remainder when \( x^{2}+3x-4 \) is divided by \( (x-1) \). By the remainder theorem, evaluate at \( x=1 \):
Rational Expressions
📌 Rational Expressions A2 · Asymptotes · Holes · Graphing rational functions · Partial fractions
A rational function is a ratio of polynomials. The new feature is the asymptote — a line the graph approaches but never meets — produced by values that make the denominator zero.
For \( y=\dfrac{1}{x-h}+k \): a vertical asymptote at \( x=h \) (denominator zero) and a horizontal asymptote at \( y=k \) (the end-behaviour value).
Slide the asymptotes around. The two amber dashed lines are \( x=h \) and \( y=k \); the curve hugs them in every corner.
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y = 1 / (x − 1)
Simplify \( \dfrac{x^{2}-9}{x-3} \). Factor and cancel (for \( x\neq 3 \)):
Solve \( \dfrac{1}{x}+\dfrac{1}{2}=1 \). Then \( \dfrac{1}{x}=\dfrac12 \), so:
A rational expression is a ratio of polynomials. Simplify by factoring and cancelling common factors. Multiply LCD to solve rational equations; check for extraneous solutions.
Simplify \( \dfrac{x^2-4}{x^2-x-2} \).
Exponential & Logarithmic Functions
📌 Exponential & Logarithmic Functions A2 · Laws of logs · Solving \(e^x=k\) · Exponential growth/decay
Exponential functions model growth and decay; logarithms are their inverses, and the tool that lets you solve for an exponent. The log laws turn products into sums.
\( \log_{a} b=c \) means exactly \( a^{c}=b \) (with \( a>0,\ a\neq 1 \)). So a logarithm is an exponent.
Solve \( 2^{x}=16 \). Write 16 as a power of 2: \( 2^{x}=2^{4} \):
Condense \( 2\log x+\log y \) to a single logarithm. Power rule then product rule:
Radicals & Rational Exponents
📌 Radicals & Rational Exponents A2 · Simplifying radicals · Rationalising · Solving radical equations
Roots and fractional exponents are two notations for the same idea. Converting between them turns awkward radical problems into routine exponent arithmetic.
\( a^{m/n}=\sqrt[n]{a^{m}}=\big(\sqrt[n]{a}\big)^{m} \). The denominator is the root; the numerator is the power.
Evaluate \( 8^{2/3} \). Take the cube root first, then square:
Solve \( \sqrt{x+3}=5 \). Square both sides: \( x+3=25 \):
Sequences & Series
📌 Sequences & Series A2 · Arithmetic & geometric · Sigma notation · Binomial theorem
Arithmetic sequences add a constant; geometric sequences multiply by one. Summing their terms gives series — including the surprising fact that an infinite geometric series can have a finite total.
An arithmetic sequence has a common difference \( d \); a geometric sequence has a common ratio \( r \). Their \( n \)th terms are \( a_1+(n-1)d \) and \( a_1 r^{\,n-1} \).
Find the 10th term of the arithmetic sequence with \( a_1=2 \), \( d=3 \).
Find the sum of \( 8+4+2+1+\cdots \) Geometric with \( a_1=8 \), \( r=\tfrac12 \):
Conic Sections
📌 Conic Sections A2 · Parabola · Ellipse · Hyperbola · Standard forms & transformations
Slice a cone and the cross-section is a circle, ellipse, parabola or hyperbola. Each has a standard equation you can read a graph straight off of.
Circle \( x^{2}+y^{2}=r^{2} \); ellipse \( \dfrac{x^{2}}{a^{2}}+\dfrac{y^{2}}{b^{2}}=1 \); parabola \( y=\dfrac{x^{2}}{4p} \); hyperbola \( \dfrac{x^{2}}{a^{2}}-\dfrac{y^{2}}{b^{2}}=1 \). A plus sign closes the curve; a minus sign opens it.
Switch between the four and stretch the defining parameter. Notice how the ellipse becomes a circle when its two radii match, and how the hyperbola's minus sign splits it into two branches.
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Equation: x²/16 + y²/9 = 1
Give the centre and radius of \( (x-2)^{2}+(y+3)^{2}=16 \). Standard circle form \( (x-h)^{2}+(y-k)^{2}=r^{2} \):
Find the vertices of \( \dfrac{x^{2}}{16}-\dfrac{y^{2}}{9}=1 \). The \( x^{2} \) term is positive, so the branches open left/right with \( a=4 \):
Conics are curves formed by intersecting a plane with a double cone: circles, ellipses, parabolas, and hyperbolas.
Identify \( 4x^2+9y^2=36 \) and find its semi-axes.
Trigonometric Functions
📌 Trigonometric Functions A2 · Unit circle · Graphs of \(\sin/\cos/\tan\) · Inverse trig · Identities
The unit circle extends sine, cosine and tangent to all angles and produces periodic graphs.
On the unit circle a point is \( (\cos\theta,\sin\theta) \). Radians: \( 180^{\circ}=\pi \). The graphs of \( \sin x \) and \( \cos x \) have period \( 2\pi \); \( \tan x \) has period \( \pi \).
Convert \( 90^{\circ} \) to radians.
Prove that \(\dfrac{\sin2\theta}{1+\cos2\theta}=\tan\theta\).
Matrices & Systems
📌 Matrices & Systems A2 · Matrix operations · Determinant · Inverse · Solving systems
A matrix is a rectangular array of numbers; matrices add, multiply, and solve linear systems.
Add matrices of the same size entrywise. For a \( 2\times2 \) matrix with rows \( (a,b) \) and \( (c,d) \), the determinant is \( ad-bc \). A system \( A\mathbf{x}=\mathbf{b} \) solves as \( \mathbf{x}=A^{-1}\mathbf{b} \) when the determinant is non-zero.
Find the determinant of the matrix with rows \( (2,1) \) and \( (3,4) \).
Use the inverse matrix method to solve \(2x+y=5\), \(x-3y=1\).
Probability & Statistics
📌 Probability & Statistics A2 · Counting · Probability rules · Normal distribution · Data analysis
Counting principles and probability describe and predict uncertain outcomes.
Permutations \( {}_nP_r=\tfrac{n!}{(n-r)!} \); combinations \( {}_nC_r=\tfrac{n!}{r!\,(n-r)!} \). Probability \( =\tfrac{\text{favourable}}{\text{total}} \).
Compute \( {}_5C_2 \).
Heights are normally distributed with \(\mu=170\) cm and \(\sigma=10\) cm. Find the probability that a randomly chosen person has height between 160 and 185 cm.
Practice set
Fifty mixed problems spanning all eight chapters — functions through conic sections — and tagged by difficulty. Click any problem to reveal a full worked solution.
If \( f(x)=2x+3 \), find \( f(4) \).
BasicIf \( f(x)=x^{2}-1 \), find \( f(-3) \).
BasicState the domain of \( f(x)=\sqrt{x-2} \).
IntermediateThe radicand must be \( \ge 0 \):
\[ x\ge 2. \]If \( f(x)=2x+1 \) and \( g(x)=x^{2} \), find \( f\big(g(2)\big) \).
Intermediate\( g(2)=4 \), then \( f(4)=9 \):
\[ 9. \]Find the inverse of \( f(x)=2x-6 \).
IntermediateIf \( f(x)=x^{2} \) and \( g(x)=x+3 \), find \( (g\circ f)(x) \).
Advanced\( g\big(f(x)\big)=g\big(x^{2}\big)=x^{2}+3 \):
\[ x^{2}+3. \]Solve \( x^{2}=49 \).
BasicSolve \( x^{2}+6x+5=0 \).
Intermediate\( (x+1)(x+5)=0 \):
\[ x=-1\ \text{or}\ x=-5. \]Find the vertex of \( y=x^{2}-4x+1 \).
Intermediate\( x=-\tfrac{b}{2a}=2 \), then \( y=4-8+1=-3 \):
\[ (2,-3). \]Find the discriminant of \( x^{2}+2x+5 \) and state the nature of the roots.
Intermediate\( \Delta=4-20=-16<0 \):
\[ \text{no real roots (two complex)}. \]Simplify \( (3+2i)+(1-5i) \).
IntermediateMultiply \( (2+i)(3-i) \).
Intermediate\( 6+i-i^{2}=6+i+1 \):
\[ 7+i. \]Solve \( x^{2}+4=0 \).
Advanced\( x^{2}=-4 \):
\[ x=\pm 2i. \]Solve \( 2x^{2}-4x-3=0 \) with the quadratic formula.
AdvancedState the degree of \( 4x^{3}-2x^{5}+7 \).
BasicDescribe the end behaviour of \( y=-x^{3} \) as \( x\to+\infty \).
IntermediateFactor \( x^{3}-9x \) completely.
IntermediateFind the remainder when \( x^{2}+3x-4 \) is divided by \( (x-1) \).
IntermediateEvaluate at \( x=1 \): \( 1+3-4 \):
\[ 0. \]Find the zeros of \( (x-2)(x+1)(x-5) \).
AdvancedThe cubic \( x^{3}-6x^{2}+11x-6 \) factors as \( (x-1)(x-2)(x-3) \). State its roots.
AdvancedSimplify \( \dfrac{x^{2}-9}{x-3} \).
BasicFactor and cancel (\( x\neq 3 \)):
\[ x+3. \]Simplify \( \dfrac{x}{2}+\dfrac{x}{3} \).
IntermediateState the vertical asymptote of \( y=\dfrac{1}{x-4} \).
IntermediateState the horizontal asymptote of \( y=\dfrac{2x}{x+1} \).
IntermediateRatio of leading coefficients:
\[ y=2. \]Solve \( \dfrac{1}{x}+\dfrac{1}{2}=1 \).
Advanced\( \dfrac{1}{x}=\dfrac12 \):
\[ x=2. \]Simplify \( \dfrac{x+1}{x^{2}-1} \).
Advanced\( x^{2}-1=(x-1)(x+1) \), cancel \( (x+1) \):
\[ \frac{1}{x-1}. \]Evaluate \( \log_{2}8 \).
Basic\( 2^{3}=8 \):
\[ 3. \]Evaluate \( \log_{10}1000 \).
BasicSolve \( 2^{x}=16 \).
IntermediateSolve \( \log_{3}x=2 \).
Intermediate\( x=3^{2} \):
\[ x=9. \]Evaluate \( \log 50+\log 2 \) (base 10).
IntermediateProduct rule: \( \log(50\times 2)=\log 100 \):
\[ 2. \]Evaluate \( \ln e^{5} \).
IntermediateSolve \( 3\cdot 2^{x}=24 \).
Advanced\( 2^{x}=8=2^{3} \):
\[ x=3. \]Condense \( 2\log x+\log y \).
AdvancedSimplify \( \sqrt{50} \).
BasicEvaluate \( 8^{2/3} \).
IntermediateSimplify \( \sqrt{12}+\sqrt{27} \).
IntermediateSolve \( \sqrt{x+3}=5 \).
IntermediateSquare: \( x+3=25 \):
\[ x=22. \]Rationalise \( \dfrac{1}{\sqrt{2}} \).
AdvancedEvaluate \( 16^{3/4} \).
AdvancedWrite the next term of \( 3,\,7,\,11,\,15,\ldots \)
BasicCommon difference 4:
\[ 19. \]Find the 10th term of the arithmetic sequence with \( a_1=2 \), \( d=3 \).
IntermediateFind the common ratio of \( 2,\,6,\,18,\,54,\ldots \)
IntermediateFind the sum \( 1+2+4+8+16 \).
IntermediateFind the sum of the infinite series \( 8+4+2+1+\cdots \)
AdvancedGeometric, \( r=\tfrac12 \):
\[ S=\frac{8}{1-\tfrac12}=16. \]Evaluate \( \displaystyle\sum_{k=1}^{4}(2k+1) \).
AdvancedGive the centre and radius of \( x^{2}+y^{2}=25 \).
BasicGive the centre and radius of \( (x-2)^{2}+(y+3)^{2}=16 \).
IntermediateIs \( \dfrac{x^{2}}{9}+\dfrac{y^{2}}{4}=1 \) an ellipse or a hyperbola?
IntermediateThe two terms are added:
\[ \text{ellipse}. \]Find the vertices of \( \dfrac{x^{2}}{16}-\dfrac{y^{2}}{9}=1 \).
AdvancedOpens left/right with \( a=4 \):
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