βž• Study Materials

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.

Ready to test yourself? Jump straight into practice.

60 WAEC & JAMB-style questions Β· 60 minutes Β· Instant score breakdown by topic

⚑ Start practice test β†’
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Number Bases

Binary, octal, denary conversions

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Indices & Logarithms

Laws of indices, log rules, standard form

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Ratio & Percentages

Profit, loss, discount, VAT, ratios

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Simple & Compound Interest

SI and CI formulas with exam applications

βœ–οΈ

Equations & Factorisation

Quadratics, simultaneous, remainder theorem

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Variation & Functions

Direct, inverse, joint variation; function notation

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Sequences & Series

AP, GP β€” nth term and sum formulas

βš–οΈ

Inequalities & Sets

Linear inequalities, Venn diagrams, set notation

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Plane Geometry

Angles, triangles, polygons, locus

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Circle Theorems

All 8 circle theorem rules tested by WAEC

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Mensuration

Areas, volumes of 2D and 3D shapes

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Coordinate Geometry

Gradient, midpoint, distance, equation of line

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Trig Ratios & Angles

SOHCAHTOA, special angles, trig identities

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Elevation & Bearings

Angles of elevation/depression, compass bearings

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Differentiation

dy/dx rules, gradient, maxima and minima

πŸ“ˆ

Integration

Indefinite and definite integrals, area under curve

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Data & Averages

Mean, median, mode, range, variance, SD

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Probability & Permutation

Theoretical probability, permutations, combinations

Overview / Number Bases

Number Bases

βœ“ WAEC Paper 1 & 2βœ“ JAMB
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What is a Number Base?

A number base tells you how many digits are used. Base 10 (denary) uses 0–9. Base 2 (binary) uses 0 and 1 only. Base 8 (octal) uses 0–7. Base 16 (hexadecimal) uses 0–9 and A–F.

WAEC and JAMB test conversions between bases and arithmetic in different bases.

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Converting to Base 10 (Expansion Method)

Multiply each digit by its base raised to its position power, then add all results.

Example β€” Convert 11010β‚‚ to base 10
Position:  4  3  2  1  0
Digit:     1  1  0  1  0
Value:  1Γ—2⁴ + 1Γ—2Β³ + 0Γ—2Β² + 1Γ—2ΒΉ + 0Γ—2⁰
      = 16 + 8 + 0 + 2 + 0 = 26
Example β€” Convert 101.11β‚‚ to decimal
1Γ—2Β² + 0Γ—2ΒΉ + 1Γ—2⁰ + 1Γ—2⁻¹ + 1Γ—2⁻²
= 4 + 0 + 1 + 0.5 + 0.25 = 5.75
⬇️
Converting from Base 10 to Another Base (Division Method)

Divide the number repeatedly by the target base. Write the remainders from bottom to top.

Example β€” Convert 26 to binary (base 2)
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‚‚ βœ“
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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.

βž•
Arithmetic in Different Bases

Carry occurs when a digit reaches the base value. In base 2, carry when you reach 2. In base 8, carry at 8.

Binary Addition β€” 1101β‚‚ + 1011β‚‚
  1 1 0 1
+ 1 0 1 1
---------
1 1 0 0 0   (= 24 in base 10: 13 + 11 = 24 βœ“)
⚠️

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.

Overview / Indices & Logarithms

Indices & Logarithms

βœ“ WAECβœ“ JAMB
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Laws of Indices
LawRuleExample
Multiplicationaᡐ Γ— aⁿ = aᡐ⁺ⁿxΒ³ Γ— x⁴ = x⁷
Divisionaᡐ ÷ aⁿ = aᡐ⁻ⁿx⁢ ÷ x² = x⁴
Power of power(aᡐ)ⁿ = aᡐⁿ(x³)² = x⁢
Zero indexa⁰ = 17⁰ = 1, x⁰ = 1
Negative indexa⁻ⁿ = 1/aⁿ2⁻³ = 1/8
Fractional indexaᡐ/ⁿ = ⁿ√(aᡐ)27β…“ = βˆ›27 = 3
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Most tested: Fractional and negative indices. Remember: 8β…” = (βˆ›8)Β² = 4. Evaluate the root first, then the power.

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Laws of Logarithms

Logarithm is the inverse of an index: if aΛ£ = N, then logₐN = x.

LawRuleExample (base 10)
Productlog(MN) = logM + logNlog(8 Γ— 125) = log8 + log125
Quotientlog(M/N) = logM βˆ’ logNlog(100/10) = log100 βˆ’ log10 = 1
Powerlog(Mⁿ) = n·logMlog(10³) = 3·log10 = 3
Base changelogₐN = logN / logΠ°logβ‚‚8 = log8 / log2 = 0.903/0.301 = 3
Special valueslogₐ1 = 0; logₐa = 1log 1 = 0; log 10 = 1
Worked Example

Simplify: log 8 + log 125 βˆ’ log 10 (base 10)
= log(8 Γ— 125) βˆ’ log 10 = log 1000 βˆ’ log 10
= log(1000/10) = log 100 = 2

⚠️

Standard form: Write numbers as A Γ— 10ⁿ where 1 ≀ A < 10. E.g. 0.004562 = 4.562 Γ— 10⁻³. To 3 significant figures: 4.56 Γ— 10⁻³.

Overview / Fractions, Ratio & Percentages

Fractions, Ratio & Percentages

βœ“ WAECβœ“ JAMB
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Profit, Loss & Discount
ConceptFormula
ProfitProfit = Selling Price βˆ’ Cost Price
% Profit% Profit = (Profit / CP) Γ— 100
LossLoss = Cost Price βˆ’ Selling Price
% Loss% Loss = (Loss / CP) Γ— 100
DiscountDiscount = Marked Price βˆ’ Selling Price
% Discount% Discount = (Discount / MP) Γ— 100
VATVAT Amount = Rate% Γ— Original Price
Example β€” % Profit

Bought for ₦15,000, sold for ₦18,000.
Profit = 18,000 βˆ’ 15,000 = ₦3,000
% Profit = (3,000 / 15,000) Γ— 100 = 20%

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Ratio, Proportion & Sharing

To share an amount in a given ratio, find the total parts, divide the amount by total parts, then multiply for each share.

Example β€” Sharing in ratio 3:5:2

Share ₦20,000 in ratio 3:5:2.
Total parts = 3+5+2 = 10
One part = ₦20,000 Γ· 10 = ₦2,000
Shares: ₦6,000 : ₦10,000 : ₦4,000

🎯

Percentage increase/decrease trap: "Increased by 20% to give 60" β†’ Original = 60 Γ· 1.2 = 50. Never divide by 0.2.

Overview / Simple & Compound Interest

Simple & Compound Interest

βœ“ WAECβœ“ JAMB
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Simple Interest (SI)

SI = (P Γ— R Γ— T) / 100
where P = Principal, R = Rate per annum, T = Time in years.
Amount = P + SI

Example

Find SI on ₦24,000 at 5% p.a. for 3 years.
SI = (24,000 Γ— 5 Γ— 3) / 100 = ₦3,600
Amount = 24,000 + 3,600 = ₦27,600

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Compound Interest (CI)

A = P(1 + R/100)α΅€
CI = A βˆ’ P

Example β€” Compound Interest

₦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 = ₦12,100
CI = 12,100 βˆ’ 10,000 = ₦2,100

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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.

Overview / Equations & Factorisation

Equations & Factorisation

βœ“ WAECβœ“ JAMB
βœ–οΈ
Quadratic Equations

Three methods: Factorisation, Formula, and Completing the square.

Factorisation β€” 2xΒ² + 5x βˆ’ 3 = 0
Find two numbers that multiply to give (2 Γ— βˆ’3 = βˆ’6)
and add to give +5: those are +6 and βˆ’1
2xΒ² + 6x βˆ’ x βˆ’ 3 = 0
2x(x + 3) βˆ’ 1(x + 3) = 0
(2x βˆ’ 1)(x + 3) = 0
x = Β½ or x = βˆ’3
Quadratic Formula β€” for axΒ² + bx + c = 0

x = [βˆ’b Β± √(bΒ² βˆ’ 4ac)] / 2a
The discriminant bΒ² βˆ’ 4ac: if > 0 β†’ 2 real roots; = 0 β†’ 1 root; < 0 β†’ no real roots.

⚑
Simultaneous Equations

Two methods: Elimination and Substitution.

Elimination β€” 2x + y = 7 and x βˆ’ y = 2
Add both equations: 3x = 9, so x = 3
Substitute: 2(3) + y = 7 β†’ y = 1
Answer: x = 3, y = 1 βœ“
πŸ”
Remainder & Factor Theorem

Remainder Theorem: When f(x) is divided by (x βˆ’ a), the remainder is f(a).
Factor Theorem: (x βˆ’ a) is a factor of f(x) if and only if f(a) = 0.

Example β€” Remainder when xΒ³ βˆ’ 5x + 3 is divided by (x βˆ’ 2)

f(2) = 2Β³ βˆ’ 5(2) + 3 = 8 βˆ’ 10 + 3 = 1

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Factorisation of difference of two squares: aΒ² βˆ’ bΒ² = (a + b)(a βˆ’ b). E.g. xΒ² βˆ’ 9 = (x+3)(xβˆ’3). Dividing by (x+3) gives (xβˆ’3).

Overview / Variation & Functions

Variation & Functions

βœ“ WAECβœ“ JAMB
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Types of Variation
TypeStatementEquationExample
Directy varies directly as xy = kxx=10,y=4 β†’ k=0.4
Inversey varies inversely as xy = k/x (xy = k)x=4,y=5 β†’ k=20
Jointy varies jointly as x and zy = kxzFind k using given values
Partialy = a + bx (partly constant)y = a + bxForm two equations, solve
Direct Variation Example

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

πŸ”§
Functions

A function f(x) maps each input x to exactly one output. To evaluate f(a), substitute x = a.

Example β€” f(x) = 3xΒ² βˆ’ 2x + 1, find f(βˆ’2)

f(βˆ’2) = 3(βˆ’2)Β² βˆ’ 2(βˆ’2) + 1 = 3(4) + 4 + 1 = 12 + 4 + 1 = 17

⚠️

Inverse function: To find f⁻¹(x), replace f(x) with y, swap x and y, then solve for y.

Overview / Sequences & Series

Sequences & Series

βœ“ WAECβœ“ JAMB
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Arithmetic Progression (AP)
FormulaMeaning
Tβ‚™ = a + (nβˆ’1)dnth term of AP. a = first term, d = common difference
Sβ‚™ = n/2[2a + (nβˆ’1)d]Sum of first n terms
Sβ‚™ = n/2(a + l)Sum using last term l
Example β€” AP: 3, 7, 11, 15... Find T₁₀ and S₁₀

a = 3, d = 4
T₁₀ = 3 + (10βˆ’1)Γ—4 = 3 + 36 = 39
S₁₀ = 10/2 Γ— [2(3) + 9(4)] = 5 Γ— [6 + 36] = 5 Γ— 42 = 210

πŸ’‘

Finding the nth term from Sβ‚™: Tβ‚™ = Sβ‚™ βˆ’ Sₙ₋₁. If Sβ‚™ = nΒ² + 2n, then Tβ‚… = Sβ‚… βˆ’ Sβ‚„ = (25+10) βˆ’ (16+8) = 35 βˆ’ 24 = 11.

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Geometric Progression (GP)
FormulaMeaning
Tβ‚™ = arⁿ⁻¹nth term. a = first term, r = common ratio
Sβ‚™ = a(rβΏβˆ’1)/(rβˆ’1) if r > 1Sum of first n terms
Sβ‚™ = a(1βˆ’rⁿ)/(1βˆ’r) if r < 1Sum of first n terms
S∞ = a/(1βˆ’r) if |r| < 1Sum to infinity
Example β€” GP: 2, 6, 18... Find T₁₀

a = 2, r = 3
T₁₀ = 2 Γ— 3⁹ = 2 Γ— 19,683 = 39,366

Overview / Inequalities & Sets

Inequalities & Sets

βœ“ WAECβœ“ JAMB
βš–οΈ
Linear Inequalities

Solve like an equation, but flip the inequality sign when multiplying or dividing by a negative number.

Example β€” 3x βˆ’ 7 > 2

3x > 2 + 7 β†’ 3x > 9 β†’ x > 3

Flip rule β€” βˆ’2x < 8

Divide by βˆ’2 and flip: x > βˆ’4

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Set Theory & Venn Diagrams
NotationMeaning
A βˆͺ BUnion β€” all elements in A or B or both
A ∩ BIntersection β€” elements in BOTH A and B
A'Complement β€” elements NOT in A
n(A βˆͺ B)n(A) + n(B) βˆ’ n(A ∩ B)
Example β€” Venn Diagram Problem

40 students: 24 passed Maths, 18 passed English, 10 passed both.
n(M βˆͺ E) = 24 + 18 βˆ’ 10 = 32 passed at least one.
Neither = 40 βˆ’ 32 = 8 failed both.

🎯

WAEC loves three-set Venn diagrams. Use: n(AβˆͺBβˆͺC) = n(A)+n(B)+n(C)βˆ’n(A∩B)βˆ’n(A∩C)βˆ’n(B∩C)+n(A∩B∩C).

Overview / Plane Geometry

Plane Geometry

βœ“ WAECβœ“ JAMB
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Angles & Lines β€” Key Rules
  • 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
πŸ”·
Triangles & Polygons
ShapeInterior Angles SumEach Interior (regular)Exterior Angle
Triangle180Β°60Β° (equilateral)= sum of two opposite interior angles
Quadrilateral360Β°90Β° (square)360Β° Γ· n
Pentagon540Β°108Β°72Β°
Hexagon720Β°120Β°60Β°
n-sided polygon(nβˆ’2) Γ— 180Β°(nβˆ’2)Γ—180Β°/n360Β°/n
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Quick formula: Sum of interior angles = (n βˆ’ 2) Γ— 180Β°. Each exterior angle of a regular polygon = 360Β° Γ· n. If exterior = 36Β°, then n = 360/36 = 10 sides.

Overview / Circle Theorems

Circle Theorems

βœ“ WAECβœ“ JAMB
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All 8 Circle Theorems β€” Memorise These
#Theorem
1The angle at the centre is twice the angle at the circumference subtended by the same arc.
2Angles in the same segment (subtended by the same chord) are equal.
3The angle in a semicircle (angle subtended by a diameter) is 90Β°.
4Opposite angles of a cyclic quadrilateral add up to 180Β°.
5The exterior angle of a cyclic quadrilateral equals the interior opposite angle.
6A radius drawn to the point of tangency is perpendicular to the tangent.
7Two tangents from an external point are equal in length.
8The perpendicular from the centre to a chord bisects the chord.
Example β€” Using Theorem 1

Angle subtended at centre = 140Β°. Angle at circumference = 140 Γ· 2 = 70Β°

Example β€” Using Theorem 4 (Cyclic Quadrilateral)

ABCD is cyclic. Angle A = 75Β°. Angle C = 180Β° βˆ’ 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.

Overview / Mensuration β€” Areas & Volumes

Mensuration

βœ“ WAECβœ“ JAMB
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2D Shapes β€” Areas & Perimeters
ShapeAreaPerimeter / Circumference
Rectanglel Γ— w2(l + w)
TriangleΒ½ Γ— b Γ— ha + b + c
TrapeziumΒ½(a + b) Γ— hSum of all sides
CircleΟ€rΒ²2Ο€r
Sector (angle ΞΈ)(ΞΈ/360) Γ— Ο€rΒ²Arc = (ΞΈ/360) Γ— 2Ο€r
πŸ’‘

Use Ο€ = 22/7 when the radius is a multiple of 7. Use Ο€ = 3.14 otherwise, unless the question specifies.

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3D Shapes β€” Surface Areas & Volumes
ShapeVolumeTotal Surface Area
Cuboidl Γ— w Γ— h2(lw + lh + wh)
CylinderΟ€rΒ²h2Ο€r(r + h)
Coneβ…“Ο€rΒ²hΟ€r(r + l) where l = slant height
Sphere4/3 Ο€rΒ³4Ο€rΒ²
Pyramidβ…“ Γ— base area Γ— hBase + Β½ Γ— perimeter Γ— slant height
Example β€” Volume of cylinder (r = 7, h = 10, Ο€ = 22/7)

V = Ο€rΒ²h = 22/7 Γ— 7Β² Γ— 10 = 22/7 Γ— 49 Γ— 10 = 22 Γ— 70 = 1,540 cmΒ³

Overview / Coordinate Geometry

Coordinate Geometry

βœ“ WAECβœ“ JAMB
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Core Formulas for Two Points (x₁,y₁) and (xβ‚‚,yβ‚‚)
ConceptFormulaExample: (1,3) and (4,9)
Gradient (slope)m = (yβ‚‚βˆ’y₁)/(xβ‚‚βˆ’x₁)m = (9βˆ’3)/(4βˆ’1) = 6/3 = 2
MidpointM = ((x₁+xβ‚‚)/2, (y₁+yβ‚‚)/2)M = (5/2, 12/2) = (2.5, 6)
Distanced = √[(xβ‚‚βˆ’x₁)Β² + (yβ‚‚βˆ’y₁)Β²]d = √[9+36] = √45 = 3√5
Equation of liney βˆ’ y₁ = m(x βˆ’ x₁)y βˆ’ 3 = 2(x βˆ’ 1) β†’ y = 2x + 1
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Parallel lines have equal gradients. Perpendicular lines: m₁ Γ— mβ‚‚ = βˆ’1. If one gradient is 2, the perpendicular gradient is βˆ’Β½.

Overview / Trig Ratios & Angles

Trig Ratios & Angles

βœ“ WAECβœ“ JAMB
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SOHCAHTOA

SOH: sin ΞΈ = Opposite / Hypotenuse
CAH: cos ΞΈ = Adjacent / Hypotenuse
TOA: tan ΞΈ = Opposite / Adjacent

Anglesincostan
0Β°010
30°½√3/21/√3
45°1/√21/√21
60°√3/2½√3
90Β°10undefined
🎯

Key identity: sinΒ²ΞΈ + cosΒ²ΞΈ = 1. This is tested in simplification questions. Always remember it.

πŸ”„
Trigonometric Graphs & Quadrants

Use the CAST rule to determine which ratios are positive in each quadrant:

  • Q1 (0°–90Β°): All (sin, cos, tan) are positive
  • Q2 (90°–180Β°): Sine only is positive
  • Q3 (180°–270Β°): Tangent only is positive
  • Q4 (270°–360Β°): Cosine only is positive
Example β€” Find all values of x if sin x = 0.5, 0Β° ≀ x ≀ 360Β°

sin⁻¹(0.5) = 30°. Sine is positive in Q1 and Q2.
x = 30Β° and x = 180Β° βˆ’ 30Β° = 150Β°

Overview / Elevation & Bearings

Angles of Elevation & Bearings

βœ“ WAECβœ“ JAMB
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Elevation & Depression

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.

Example β€” Tower Problem

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/√3 = 50/√3 = 50√3/3 β‰ˆ 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

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°
Overview / Differentiation

Differentiation

βœ“ WAEC (Further Maths & Maths)βœ“ JAMB
πŸ“‰
Basic Rules of Differentiation
FunctionDerivative dy/dx
y = xⁿdy/dx = nxⁿ⁻¹
y = axⁿdy/dx = naxⁿ⁻¹
y = constantdy/dx = 0
y = axΒ² + bx + cdy/dx = 2ax + b
Example β€” Differentiate y = 4xΒ³ βˆ’ 3xΒ² + 2x βˆ’ 5

dy/dx = 12xΒ² βˆ’ 6x + 2

Gradient at a point β€” find gradient of y = 3xΒ² βˆ’ 5x + 1 at x = 2

dy/dx = 6x βˆ’ 5. At x = 2: gradient = 6(2) βˆ’ 5 = 7

🎯
Maximum & Minimum Points

At a maximum or minimum, dy/dx = 0. To distinguish:
β€’ If dΒ²y/dxΒ² < 0 β†’ Maximum
β€’ If dΒ²y/dxΒ² > 0 β†’ Minimum

Example β€” Find maximum of y = 4 βˆ’ xΒ²

dy/dx = βˆ’2x = 0 β†’ x = 0
y_max = 4 βˆ’ 0 = 4
dΒ²y/dxΒ² = βˆ’2 < 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 = βˆ’1 Γ· (dy/dx).

Overview / Integration

Integration

βœ“ WAECβœ“ JAMB
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Basic Integration Rules

Integration is the reverse of differentiation.
∫ xⁿ dx = xⁿ⁺¹/(n+1) + C (indefinite integral, n β‰  βˆ’1)

Indefinite Integral β€” ∫ (2x + 3) dx

= 2xΒ²/2 + 3x + C = xΒ² + 3x + C

πŸ“Š
Definite Integrals & Area Under a Curve

For βˆ«β‚α΅‡ f(x) dx: integrate, then evaluate at x = b and subtract evaluation at x = a.

Example β€” βˆ«β‚€Β² (xΒ² + 1) dx
= [xΒ³/3 + x]β‚€Β²
= (8/3 + 2) βˆ’ (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).

Overview / Data, Averages & Spread

Data, Averages & Spread

βœ“ WAECβœ“ JAMB
πŸ“Š
Measures of Central Tendency
MeasureDefinitionHow to Find
MeanAverage valueSum of all values Γ· number of values
MedianMiddle valueArrange in order; middle value (odd n) or average of two middle (even n)
ModeMost frequent valueValue that appears most often
RangeSpreadLargest βˆ’ Smallest
Example β€” Mean: 5 numbers with mean 12, four are 10,14,15,9

Sum = 5 Γ— 12 = 60. Sum of known = 10+14+15+9 = 48. Fifth number = 60 βˆ’ 48 = 12

πŸ“
Variance & Standard Deviation

Variance (σ²) = mean of squared deviations from the mean = Ξ£(x βˆ’ xΜ„)Β²/n
Standard Deviation (Οƒ) = √(Variance)

Key Relationship

If Variance = 16, then Standard Deviation = √16 = 4

🎯

Frequency table mean: Use xΜ„ = Ξ£(fx) / Ξ£f where f = frequency and x = midpoint of class interval for grouped data.

Overview / Probability & Permutation

Probability & Permutation

βœ“ WAECβœ“ JAMB
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Probability

P(event) = Number of favourable outcomes / Total possible outcomes

RuleFormula
ComplementP(A') = 1 βˆ’ P(A)
Addition (mutually exclusive)P(A or B) = P(A) + P(B)
Addition (not exclusive)P(A βˆͺ B) = P(A) + P(B) βˆ’ P(A ∩ B)
Multiplication (independent)P(A and B) = P(A) Γ— P(B)
Example β€” Ball Probability

Bag: 4 red, 6 blue balls. P(red) = 4/10 = 2/5

πŸ”’
Permutations & Combinations
ConceptFormulaExample
Permutation (order matters)ⁿPr = n! / (nβˆ’r)!4 students in a row: ⁴Pβ‚„ = 4! = 24
Combination (order doesn't matter)ⁿCr = n! / [r!(nβˆ’r)!]Choose 3 from 5: ⁡C₃ = 10
Factorial examples

4! = 4 Γ— 3 Γ— 2 Γ— 1 = 24  |  5! = 120  |  0! = 1 (by definition)

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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.

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