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Mathematics
Study Notes
All notes follow the official WAEC and JAMB approved syllabus. Study a topic first, then take the practice quiz β after the test, come back here to see which topics you need to improve.
Number Bases
Binary, octal, denary conversions
Indices & Logarithms
Laws of indices, log rules, standard form
Ratio & Percentages
Profit, loss, discount, VAT, ratios
Simple & Compound Interest
SI and CI formulas with exam applications
Equations & Factorisation
Quadratics, simultaneous, remainder theorem
Variation & Functions
Direct, inverse, joint variation; function notation
Sequences & Series
AP, GP β nth term and sum formulas
Inequalities & Sets
Linear inequalities, Venn diagrams, set notation
Plane Geometry
Angles, triangles, polygons, locus
Circle Theorems
All 8 circle theorem rules tested by WAEC
Mensuration
Areas, volumes of 2D and 3D shapes
Coordinate Geometry
Gradient, midpoint, distance, equation of line
Trig Ratios & Angles
SOHCAHTOA, special angles, trig identities
Elevation & Bearings
Angles of elevation/depression, compass bearings
Differentiation
dy/dx rules, gradient, maxima and minima
Integration
Indefinite and definite integrals, area under curve
Data & Averages
Mean, median, mode, range, variance, SD
Probability & Permutation
Theoretical probability, permutations, combinations
Number Bases
A number base tells you how many digits are used. Base 10 (denary) uses 0β9. Base 2 (binary) uses 0 and 1 only. Base 8 (octal) uses 0β7. Base 16 (hexadecimal) uses 0β9 and AβF.
WAEC and JAMB test conversions between bases and arithmetic in different bases.
Multiply each digit by its base raised to its position power, then add all results.
Position: 4 3 2 1 0
Digit: 1 1 0 1 0
Value: 1Γ2β΄ + 1Γ2Β³ + 0Γ2Β² + 1Γ2ΒΉ + 0Γ2β°
= 16 + 8 + 0 + 2 + 0 = 26
1Γ2Β² + 0Γ2ΒΉ + 1Γ2β° + 1Γ2β»ΒΉ + 1Γ2β»Β² = 4 + 0 + 1 + 0.5 + 0.25 = 5.75
Divide the number repeatedly by the target base. Write the remainders from bottom to top.
26 Γ· 2 = 13 remainder 0 13 Γ· 2 = 6 remainder 1 6 Γ· 2 = 3 remainder 0 3 Γ· 2 = 1 remainder 1 1 Γ· 2 = 0 remainder 1 Reading remainders bottom to top: 11010β β
Exam shortcut: For binary to octal or hex, group the binary digits in sets of 3 (octal) or 4 (hex) from the right, then convert each group directly.
Carry occurs when a digit reaches the base value. In base 2, carry when you reach 2. In base 8, carry at 8.
1 1 0 1 + 1 0 1 1 --------- 1 1 0 0 0 (= 24 in base 10: 13 + 11 = 24 β)
WAEC tests subtraction and multiplication in non-decimal bases. Always verify your answer by converting both the question and your answer to base 10 to check.
Indices & Logarithms
| Law | Rule | Example |
|---|---|---|
| Multiplication | aα΅ Γ aβΏ = aα΅βΊβΏ | xΒ³ Γ xβ΄ = xβ· |
| Division | aα΅ Γ· aβΏ = aα΅β»βΏ | xβΆ Γ· xΒ² = xβ΄ |
| Power of power | (aα΅)βΏ = aα΅βΏ | (xΒ³)Β² = xβΆ |
| Zero index | aβ° = 1 | 7β° = 1, xβ° = 1 |
| Negative index | aβ»βΏ = 1/aβΏ | 2β»Β³ = 1/8 |
| Fractional index | aα΅/βΏ = βΏβ(aα΅) | 27β = β27 = 3 |
Most tested: Fractional and negative indices. Remember: 8β = (β8)Β² = 4. Evaluate the root first, then the power.
Logarithm is the inverse of an index: if aΛ£ = N, then logβN = x.
| Law | Rule | Example (base 10) |
|---|---|---|
| Product | log(MN) = logM + logN | log(8 Γ 125) = log8 + log125 |
| Quotient | log(M/N) = logM β logN | log(100/10) = log100 β log10 = 1 |
| Power | log(MβΏ) = nΒ·logM | log(10Β³) = 3Β·log10 = 3 |
| Base change | logβN = logN / logΠ° | logβ8 = log8 / log2 = 0.903/0.301 = 3 |
| Special values | logβ1 = 0; logβa = 1 | log 1 = 0; log 10 = 1 |
Simplify: log 8 + log 125 β log 10 (base 10)
= log(8 Γ 125) β log 10 = log 1000 β log 10
= log(1000/10) = log 100 = 2
Standard form: Write numbers as A Γ 10βΏ where 1 β€ A < 10. E.g. 0.004562 = 4.562 Γ 10β»Β³. To 3 significant figures: 4.56 Γ 10β»Β³.
Fractions, Ratio & Percentages
| Concept | Formula |
|---|---|
| Profit | Profit = Selling Price β Cost Price |
| % Profit | % Profit = (Profit / CP) Γ 100 |
| Loss | Loss = Cost Price β Selling Price |
| % Loss | % Loss = (Loss / CP) Γ 100 |
| Discount | Discount = Marked Price β Selling Price |
| % Discount | % Discount = (Discount / MP) Γ 100 |
| VAT | VAT Amount = Rate% Γ Original Price |
Bought for β¦15,000, sold for β¦18,000.
Profit = 18,000 β 15,000 = β¦3,000
% Profit = (3,000 / 15,000) Γ 100 = 20%
To share an amount in a given ratio, find the total parts, divide the amount by total parts, then multiply for each share.
Share β¦20,000 in ratio 3:5:2.
Total parts = 3+5+2 = 10
One part = β¦20,000 Γ· 10 = β¦2,000
Shares: β¦6,000 : β¦10,000 : β¦4,000
Percentage increase/decrease trap: "Increased by 20% to give 60" β Original = 60 Γ· 1.2 = 50. Never divide by 0.2.
Simple & Compound Interest
SI = (P Γ R Γ T) / 100
where P = Principal, R = Rate per annum, T = Time in years.
Amount = P + SI
Find SI on β¦24,000 at 5% p.a. for 3 years.
SI = (24,000 Γ 5 Γ 3) / 100 = β¦3,600
Amount = 24,000 + 3,600 = β¦27,600
A = P(1 + R/100)α΅
CI = A β P
β¦10,000 at 10% p.a. for 2 years, compounded annually.
A = 10,000 Γ (1 + 10/100)Β² = 10,000 Γ 1.1Β² = 10,000 Γ 1.21 = β¦12,100
CI = 12,100 β 10,000 = β¦2,100
Key difference: Simple interest is calculated on the original principal only. Compound interest is calculated on the growing amount each period. CI always gives more than SI for the same rate and time.
Equations & Factorisation
Three methods: Factorisation, Formula, and Completing the square.
Find two numbers that multiply to give (2 Γ β3 = β6) and add to give +5: those are +6 and β1 2xΒ² + 6x β x β 3 = 0 2x(x + 3) β 1(x + 3) = 0 (2x β 1)(x + 3) = 0 x = Β½ or x = β3
x = [βb Β± β(bΒ² β 4ac)] / 2a
The discriminant bΒ² β 4ac: if > 0 β 2 real roots; = 0 β 1 root; < 0 β no real roots.
Two methods: Elimination and Substitution.
Add both equations: 3x = 9, so x = 3 Substitute: 2(3) + y = 7 β y = 1 Answer: x = 3, y = 1 β
Remainder Theorem: When f(x) is divided by (x β a), the remainder is f(a).
Factor Theorem: (x β a) is a factor of f(x) if and only if f(a) = 0.
f(2) = 2Β³ β 5(2) + 3 = 8 β 10 + 3 = 1
Factorisation of difference of two squares: aΒ² β bΒ² = (a + b)(a β b). E.g. xΒ² β 9 = (x+3)(xβ3). Dividing by (x+3) gives (xβ3).
Variation & Functions
| Type | Statement | Equation | Example |
|---|---|---|---|
| Direct | y varies directly as x | y = kx | x=10,y=4 β k=0.4 |
| Inverse | y varies inversely as x | y = k/x (xy = k) | x=4,y=5 β k=20 |
| Joint | y varies jointly as x and z | y = kxz | Find k using given values |
| Partial | y = a + bx (partly constant) | y = a + bx | Form two equations, solve |
x varies directly as y. x = 10 when y = 4. Find x when y = 10.
y = kx β 10 = k Γ 4 β k = 2.5
When y = 10: x = 2.5 Γ 10 = 25
A function f(x) maps each input x to exactly one output. To evaluate f(a), substitute x = a.
f(β2) = 3(β2)Β² β 2(β2) + 1 = 3(4) + 4 + 1 = 12 + 4 + 1 = 17
Inverse function: To find fβ»ΒΉ(x), replace f(x) with y, swap x and y, then solve for y.
Sequences & Series
| Formula | Meaning |
|---|---|
| Tβ = a + (nβ1)d | nth term of AP. a = first term, d = common difference |
| Sβ = n/2[2a + (nβ1)d] | Sum of first n terms |
| Sβ = n/2(a + l) | Sum using last term l |
a = 3, d = 4
Tββ = 3 + (10β1)Γ4 = 3 + 36 = 39
Sββ = 10/2 Γ [2(3) + 9(4)] = 5 Γ [6 + 36] = 5 Γ 42 = 210
Finding the nth term from Sβ: Tβ = Sβ β Sβββ. If Sβ = nΒ² + 2n, then Tβ = Sβ β Sβ = (25+10) β (16+8) = 35 β 24 = 11.
| Formula | Meaning |
|---|---|
| Tβ = arβΏβ»ΒΉ | nth term. a = first term, r = common ratio |
| Sβ = a(rβΏβ1)/(rβ1) if r > 1 | Sum of first n terms |
| Sβ = a(1βrβΏ)/(1βr) if r < 1 | Sum of first n terms |
| Sβ = a/(1βr) if |r| < 1 | Sum to infinity |
a = 2, r = 3
Tββ = 2 Γ 3βΉ = 2 Γ 19,683 = 39,366
Inequalities & Sets
Solve like an equation, but flip the inequality sign when multiplying or dividing by a negative number.
3x > 2 + 7 β 3x > 9 β x > 3
Divide by β2 and flip: x > β4
| Notation | Meaning |
|---|---|
| A βͺ B | Union β all elements in A or B or both |
| A β© B | Intersection β elements in BOTH A and B |
| A' | Complement β elements NOT in A |
| n(A βͺ B) | n(A) + n(B) β n(A β© B) |
40 students: 24 passed Maths, 18 passed English, 10 passed both.
n(M βͺ E) = 24 + 18 β 10 = 32 passed at least one.
Neither = 40 β 32 = 8 failed both.
WAEC loves three-set Venn diagrams. Use: n(AβͺBβͺC) = n(A)+n(B)+n(C)βn(Aβ©B)βn(Aβ©C)βn(Bβ©C)+n(Aβ©Bβ©C).
Plane Geometry
- Angles on a straight line add up to 180Β°
- Angles at a point add up to 360Β°
- Vertically opposite angles are equal
- Alternate angles (Z-angles) are equal when lines are parallel
- Co-interior angles (C-angles) add up to 180Β° when lines are parallel
- Corresponding angles (F-angles) are equal when lines are parallel
| Shape | Interior Angles Sum | Each Interior (regular) | Exterior Angle |
|---|---|---|---|
| Triangle | 180Β° | 60Β° (equilateral) | = sum of two opposite interior angles |
| Quadrilateral | 360Β° | 90Β° (square) | 360Β° Γ· n |
| Pentagon | 540Β° | 108Β° | 72Β° |
| Hexagon | 720Β° | 120Β° | 60Β° |
| n-sided polygon | (nβ2) Γ 180Β° | (nβ2)Γ180Β°/n | 360Β°/n |
Quick formula: Sum of interior angles = (n β 2) Γ 180Β°. Each exterior angle of a regular polygon = 360Β° Γ· n. If exterior = 36Β°, then n = 360/36 = 10 sides.
Circle Theorems
| # | Theorem |
|---|---|
| 1 | The angle at the centre is twice the angle at the circumference subtended by the same arc. |
| 2 | Angles in the same segment (subtended by the same chord) are equal. |
| 3 | The angle in a semicircle (angle subtended by a diameter) is 90Β°. |
| 4 | Opposite angles of a cyclic quadrilateral add up to 180Β°. |
| 5 | The exterior angle of a cyclic quadrilateral equals the interior opposite angle. |
| 6 | A radius drawn to the point of tangency is perpendicular to the tangent. |
| 7 | Two tangents from an external point are equal in length. |
| 8 | The perpendicular from the centre to a chord bisects the chord. |
Angle subtended at centre = 140Β°. Angle at circumference = 140 Γ· 2 = 70Β°
ABCD is cyclic. Angle A = 75Β°. Angle C = 180Β° β 75Β° = 105Β°
Most tested: Theorem 1 (centre = 2 Γ circumference), Theorem 3 (angle in semicircle = 90Β°), Theorem 4 (cyclic quad opposite angles = 180Β°). These appear every year.
Mensuration
| Shape | Area | Perimeter / Circumference |
|---|---|---|
| Rectangle | l Γ w | 2(l + w) |
| Triangle | Β½ Γ b Γ h | a + b + c |
| Trapezium | Β½(a + b) Γ h | Sum of all sides |
| Circle | ΟrΒ² | 2Οr |
| Sector (angle ΞΈ) | (ΞΈ/360) Γ ΟrΒ² | Arc = (ΞΈ/360) Γ 2Οr |
Use Ο = 22/7 when the radius is a multiple of 7. Use Ο = 3.14 otherwise, unless the question specifies.
| Shape | Volume | Total Surface Area |
|---|---|---|
| Cuboid | l Γ w Γ h | 2(lw + lh + wh) |
| Cylinder | ΟrΒ²h | 2Οr(r + h) |
| Cone | β ΟrΒ²h | Οr(r + l) where l = slant height |
| Sphere | 4/3 ΟrΒ³ | 4ΟrΒ² |
| Pyramid | β Γ base area Γ h | Base + Β½ Γ perimeter Γ slant height |
V = ΟrΒ²h = 22/7 Γ 7Β² Γ 10 = 22/7 Γ 49 Γ 10 = 22 Γ 70 = 1,540 cmΒ³
Coordinate Geometry
| Concept | Formula | Example: (1,3) and (4,9) |
|---|---|---|
| Gradient (slope) | m = (yββyβ)/(xββxβ) | m = (9β3)/(4β1) = 6/3 = 2 |
| Midpoint | M = ((xβ+xβ)/2, (yβ+yβ)/2) | M = (5/2, 12/2) = (2.5, 6) |
| Distance | d = β[(xββxβ)Β² + (yββyβ)Β²] | d = β[9+36] = β45 = 3β5 |
| Equation of line | y β yβ = m(x β xβ) | y β 3 = 2(x β 1) β y = 2x + 1 |
Parallel lines have equal gradients. Perpendicular lines: mβ Γ mβ = β1. If one gradient is 2, the perpendicular gradient is βΒ½.
Trig Ratios & Angles
SOH: sin ΞΈ = Opposite / Hypotenuse
CAH: cos ΞΈ = Adjacent / Hypotenuse
TOA: tan ΞΈ = Opposite / Adjacent
| Angle | sin | cos | tan |
|---|---|---|---|
| 0Β° | 0 | 1 | 0 |
| 30Β° | Β½ | β3/2 | 1/β3 |
| 45Β° | 1/β2 | 1/β2 | 1 |
| 60Β° | β3/2 | Β½ | β3 |
| 90Β° | 1 | 0 | undefined |
Key identity: sinΒ²ΞΈ + cosΒ²ΞΈ = 1. This is tested in simplification questions. Always remember it.
Use the CAST rule to determine which ratios are positive in each quadrant:
- Q1 (0Β°β90Β°): All (sin, cos, tan) are positive
- Q2 (90Β°β180Β°): Sine only is positive
- Q3 (180Β°β270Β°): Tangent only is positive
- Q4 (270Β°β360Β°): Cosine only is positive
sinβ»ΒΉ(0.5) = 30Β°. Sine is positive in Q1 and Q2.
x = 30Β° and x = 180Β° β 30Β° = 150Β°
Angles of Elevation & Bearings
Angle of elevation: the angle measured upward from the horizontal to an object above.
Angle of depression: the angle measured downward from the horizontal to an object below.
A man stands 50m from the base of a tower. Angle of elevation = 30Β°.
tan 30Β° = height / 50
height = 50 Γ tan 30Β° = 50 Γ 1/β3 = 50/β3 = 50β3/3 β 28.9m
The angle of elevation from A to B equals the angle of depression from B to A (alternate angles). Draw a diagram for every elevation/depression question.
Bearings are measured clockwise from North and always written as 3 digits. N=000Β°, E=090Β°, S=180Β°, W=270Β°.
- Bearing of N45Β°E = 045Β°
- Bearing of S60Β°W = 180Β° + 60Β° = 240Β°
- Back bearing (reverse direction): add or subtract 180Β°
Differentiation
| Function | Derivative dy/dx |
|---|---|
| y = xβΏ | dy/dx = nxβΏβ»ΒΉ |
| y = axβΏ | dy/dx = naxβΏβ»ΒΉ |
| y = constant | dy/dx = 0 |
| y = axΒ² + bx + c | dy/dx = 2ax + b |
dy/dx = 12xΒ² β 6x + 2
dy/dx = 6x β 5. At x = 2: gradient = 6(2) β 5 = 7
At a maximum or minimum, dy/dx = 0. To distinguish:
β’ If dΒ²y/dxΒ² < 0 β Maximum
β’ If dΒ²y/dxΒ² > 0 β Minimum
dy/dx = β2x = 0 β x = 0
y_max = 4 β 0 = 4
dΒ²y/dxΒ² = β2 < 0 β confirmed maximum
JAMB and WAEC also ask for the equation of the tangent and normal to a curve at a point. Tangent gradient = dy/dx at the point. Normal gradient = β1 Γ· (dy/dx).
Integration
Integration is the reverse of differentiation.
β« xβΏ dx = xβΏβΊΒΉ/(n+1) + C (indefinite integral, n β β1)
= 2xΒ²/2 + 3x + C = xΒ² + 3x + C
For β«βα΅ f(x) dx: integrate, then evaluate at x = b and subtract evaluation at x = a.
= [xΒ³/3 + x]βΒ² = (8/3 + 2) β (0 + 0) = 8/3 + 6/3 = 14/3
Area between a curve and the x-axis is the definite integral (take absolute value if the area is below the x-axis, i.e., the integral gives a negative result).
Data, Averages & Spread
| Measure | Definition | How to Find |
|---|---|---|
| Mean | Average value | Sum of all values Γ· number of values |
| Median | Middle value | Arrange in order; middle value (odd n) or average of two middle (even n) |
| Mode | Most frequent value | Value that appears most often |
| Range | Spread | Largest β Smallest |
Sum = 5 Γ 12 = 60. Sum of known = 10+14+15+9 = 48. Fifth number = 60 β 48 = 12
Variance (ΟΒ²) = mean of squared deviations from the mean = Ξ£(x β xΜ)Β²/n
Standard Deviation (Ο) = β(Variance)
If Variance = 16, then Standard Deviation = β16 = 4
Frequency table mean: Use xΜ = Ξ£(fx) / Ξ£f where f = frequency and x = midpoint of class interval for grouped data.
Probability & Permutation
P(event) = Number of favourable outcomes / Total possible outcomes
| Rule | Formula |
|---|---|
| Complement | P(A') = 1 β P(A) |
| Addition (mutually exclusive) | P(A or B) = P(A) + P(B) |
| Addition (not exclusive) | P(A βͺ B) = P(A) + P(B) β P(A β© B) |
| Multiplication (independent) | P(A and B) = P(A) Γ P(B) |
Bag: 4 red, 6 blue balls. P(red) = 4/10 = 2/5
| Concept | Formula | Example |
|---|---|---|
| Permutation (order matters) | βΏPr = n! / (nβr)! | 4 students in a row: β΄Pβ = 4! = 24 |
| Combination (order doesn't matter) | βΏCr = n! / [r!(nβr)!] | Choose 3 from 5: β΅Cβ = 10 |
4! = 4 Γ 3 Γ 2 Γ 1 = 24 | 5! = 120 | 0! = 1 (by definition)
Key distinction: Arrangements (order matters) β Permutation. Selections/groups (order doesn't matter) β Combination. "How many ways can 4 sit in a row" β nPr. "Choose a committee of 3 from 8" β nCr.
You've now covered all major WAEC and JAMB Mathematics topics. Take the 60-question timed CBT practice to see your score and get a personalised breakdown by topic.