Grade 10 Mathematics
Grade 10 ยท Term 1Mathematics

Exponents, Equations & Inequalities

We revise and extend the laws of exponents to rational exponents, then solve every type of equation met in Grade 10: linear, quadratic (by factorisation), simultaneous, and literal. We close by solving linear inequalities and displaying the solution on a number line.

Week 7

2.1 Laws of Exponents

  • Revise laws of exponents for integer exponents ($m,n\in\mathbb{Z}$)
  • Use the laws for rational exponents ($m,n\in\mathbb{Q}$)
  • Simplify and solve exponential expressions
๐ŸŒ

Real-World Connection

Every memory card, hard drive, and phone plan is measured in powers of 2: 4 GB, 8 GB, 16 GB, 32 GBโ€ฆ When engineers combine two memory banks of $2^{10}$ bytes each, they know instantly: $2^{10}\times2^{10}=2^{20}$ bytes = 1 MB. The exponent law $a^m\cdot a^n=a^{m+n}$ is not an abstract rule โ€” it is why all digital technology uses base-2 storage.

Product rule

amโ‹…an=am+na^m\cdot a^n = a^{m+n}

Same base; add exponents.

Quotient rule

aman=amโˆ’nโ€…โ€Š(aโ‰ 0)\dfrac{a^m}{a^n} = a^{m-n}\;(a\neq0)

Same base; subtract exponents.

Power of a power

(am)n=amn(a^m)^n = a^{mn}

Multiply exponents.

Power of a product

(ab)n=anbn(ab)^n = a^n b^n

Distribute exponent over the product.

Negative exponent

aโˆ’n=1anโ€…โ€Š(aโ‰ 0)a^{-n} = \dfrac{1}{a^n}\;(a\neq0)

Reciprocate; make exponent positive.

Zero exponent

a0=1โ€…โ€Š(aโ‰ 0)a^0 = 1\;(a\neq0)

Any non-zero base to power 0 equals 1.

Rational exponent

am/n=amn=(an)ma^{m/n} = \sqrt[n]{a^m} = (\sqrt[n]{a})^m

Denominator = root index; numerator = power.

๐Ÿšจ Common Mistake

(โˆ’2)4=16(-2)^4=16 but โˆ’24=โˆ’16-2^4=-16. The base of an exponent is only what is in brackets. When in doubt, add brackets.

Worked Examples

Worked Example

Simplify using exponent laws

Problem

Simplify: 2n+2โ‹…4nโˆ’18n\dfrac{2^{n+2}\cdot4^{n-1}}{8^n}

Worked Example

Rational Exponents

Problem

Evaluate: (278)โˆ’2/3\left(\dfrac{27}{8}\right)^{-2/3}
Activity โ€” 8 Questions

CAPS Cognitive Level Distribution

L1 ยท Knowledge2 Q
L2 ยท Routine Procedures2 Q
L3 ยท Complex Procedures2 Q
L4 ยท Problem Solving2 Q
1
L1 ยท Knowledge1 mark
Write xโˆ’3x^{-3} without negative exponents.
2
L1 ยท Knowledge2 marks
Evaluate (14)1/2\left(\dfrac{1}{4}\right)^{1/2}.
3
L2 ยท Routine Procedures3 marks
Simplify a3โ‹…aโˆ’1aโˆ’2\dfrac{a^3\cdot a^{-1}}{a^{-2}}.
4
L2 ยท Routine Procedures3 marks
Simplify 3x+1โˆ’3x3x\dfrac{3^{x+1}-3^x}{3^x}.
5
L3 ยท Complex Procedures4 marks
Simplify 22xโˆ’42x+2\dfrac{2^{2x}-4}{2^x+2}.
6
L3 ยท Complex Procedures5 marks
Simplify 6nโ‹…92nโˆ’1โ‹…3n+2\dfrac{6^n\cdot9}{2^{n-1}\cdot3^{n+2}}.
7
L4 ยท Problem Solving5 marks
If 2x=32^x=3, find 4xโˆ’2x+14^x-2^{x+1}.
8
L4 ยท Problem Solving6 marks
Solve for xx: 22xโˆ’5โ‹…2x+4=02^{2x}-5\cdot2^x+4=0.
Week 8

2.2 Equations

  • Revise and solve linear equations
  • Solve quadratic equations by factorisation
  • Solve simultaneous linear equations in two unknowns
  • Solve literal equations (changing the subject)
  • Solve word problems involving linear, quadratic or simultaneous equations
๐ŸŒ

Real-World Connection

A pharmacist mixing a solution needs an exact concentration โ€” too much or too little and the medicine is wrong. The equation $2x+15=63$ is that precise constraint: $x$ is the unknown volume and the equation says the total must be exactly 63 ml. Solving it finds the one measurement that satisfies the prescription โ€” and any method is valid as long as you treat both sides of the scale equally.

Property / Rule

Zero Product Property

If a product equals zero, at least one factor must be zero. This is the foundation for solving quadratic equations by factorisation.

AB=0โ‡’A=0ย orย B=0AB=0 \Rightarrow A=0 \text{ or } B=0

Property / Rule

Solving simultaneous linear equations

Substitution: express one variable in terms of the other from one equation, then substitute into the second. Elimination: make coefficients of one variable equal and subtract (or add) the equations.

{y=2x+13xโˆ’y=4\begin{cases} y=2x+1 \\ 3x-y=4 \end{cases}

Property / Rule

Literal equations (changing the subject)

Use the same algebraic operations as solving any equation, but the answer will be in terms of other letters rather than numbers.

A=ฯ€r2โ‡’r=Aฯ€A=\pi r^2 \Rightarrow r = \sqrt{\dfrac{A}{\pi}}

๐Ÿšจ Common Mistake

ALWAYS rearrange a quadratic to standard form ax2+bx+c=0ax^2+bx+c=0 BEFORE factorising. Never divide both sides by xx โ€” this loses the solution x=0x=0.

Worked Examples

Worked Example

Solve a quadratic by factorisation

Problem

Solve: x2โˆ’x=6x^2-x=6

Worked Example

Simultaneous linear equations

Problem

Solve: 2x+y=72x+y=7 and xโˆ’y=2x-y=2

Worked Example

Literal equation โ€” changing the subject

Problem

Make hh the subject of A=12h(a+b)A = \dfrac{1}{2}h(a+b).

Worked Example

Word problem โ€” setting up and solving an equation

Problem

The sum of three consecutive integers is 57. Find the three integers.
Activity โ€” 8 Questions

CAPS Cognitive Level Distribution

L1 ยท Knowledge2 Q
L2 ยท Routine Procedures2 Q
L3 ยท Complex Procedures2 Q
L4 ยท Problem Solving2 Q
1
L1 ยท Knowledge2 marks
Solve 3xโˆ’7=23x-7=2.
2
L1 ยท Knowledge2 marks
Solve x2=16x^2=16.
3
L2 ยท Routine Procedures3 marks
Solve x2+5xโˆ’14=0x^2+5x-14=0 by factorisation.
4
L2 ยท Routine Procedures4 marks
Solve simultaneously: y=3xโˆ’1y=3x-1 and 2x+y=92x+y=9.
5
L3 ยท Complex Procedures5 marks
Solve 2xxโˆ’1โˆ’xx+1=4x2โˆ’1\dfrac{2x}{x-1}-\dfrac{x}{x+1}=\dfrac{4}{x^2-1}, xโ‰ ยฑ1x\neq\pm1.
6
L3 ยท Complex Procedures4 marks
Make rr the subject of V=43ฯ€r3V=\dfrac{4}{3}\pi r^3.
7
L4 ยท Problem Solving5 marks
Twice a number squared is 5 more than 9 times the number. Find all possible values.
8
L4 ยท Problem Solving5 marks
For what value(s) of kk does kx2โˆ’6x+9=0kx^2-6x+9=0 have equal roots?
Week 9

2.3 Linear Inequalities

  • Solve linear inequalities and show the solution graphically on a number line
  • Work with compound inequalities (AND/OR)
  • Express solutions using interval notation
๐ŸŒ

Real-World Connection

An inequality is not a single answer but a region of answers. 'You must be taller than 1ยท5 m to ride this attraction' is an inequality โ€” it describes all heights above 1ยท5 m, not one specific height.

Property / Rule

Inequality Rules

You can add/subtract the same quantity on both sides. Multiplying or dividing by a POSITIVE number preserves the direction. Multiplying or dividing by a NEGATIVE number REVERSES the direction.

Ifย a>bย andย c<0,ย thenย ac<bc\text{If }a>b\text{ and }c<0,\text{ then }ac<bc

Property / Rule

Number line and interval notation

Open circle โ—‹ at an endpoint means that value is EXCLUDED (<< or >>). Closed circle โ— means INCLUDED (โ‰ค\leq or โ‰ฅ\geq). Interval notation: round bracket for excluded, square bracket for included.

x>3:โ€…โ€Šxโˆˆ(3;โˆž)xโ‰คโˆ’1:โ€…โ€Šxโˆˆ(โˆ’โˆž;โˆ’1]x>3:\;x\in(3;\infty) \qquad x\leq-1:\;x\in(-\infty;-1]

๐Ÿšจ Common Mistake

THE most common error: forgetting to flip the sign when multiplying or dividing by a negative number. โˆ’2x<6-2x<6 does NOT give x<โˆ’3x<-3; it gives x>โˆ’3x>-3.

Worked Examples

Worked Example

Compound inequality

Problem

Solve and represent on a number line: โˆ’3<2x+1โ‰ค7-3 < 2x+1 \leq 7
Activity โ€” 8 Questions

CAPS Cognitive Level Distribution

L1 ยท Knowledge2 Q
L2 ยท Routine Procedures2 Q
L3 ยท Complex Procedures2 Q
L4 ยท Problem Solving2 Q
1
L1 ยท Knowledge2 marks
Is x=5x=5 a solution to 3xโˆ’4>113x-4>11?
2
L1 ยท Knowledge1 mark
What happens to the inequality sign when you divide both sides by โˆ’4-4?
3
L2 ยท Routine Procedures3 marks
Solve 5x+2โ‰ฅ3xโˆ’65x+2\geq3x-6 and represent on a number line.
4
L2 ยท Routine Procedures4 marks
Solve โˆ’2โ‰คxโˆ’32<4-2\leq\dfrac{x-3}{2}<4. Express in interval notation.
5
L3 ยท Complex Procedures5 marks
Solve 3xโˆ’14>2x+33\dfrac{3x-1}{4}>\dfrac{2x+3}{3}.
6
L3 ยท Complex Procedures4 marks
Find integer values of xx satisfying โˆ’5<3โˆ’2xโ‰ค9-5<3-2x\leq9.
7
L4 ยท Problem Solving5 marks
A rectangle has length 2x+32x+3 and width x+1x+1. For what values of xx is the perimeter greater than 38?
8
L4 ยท Problem Solving4 marks
For what real values of xx is 1x+2>0\dfrac{1}{x+2}>0?
Exponents, Equations & Inequalities Grade 10 Maths CAPS Notes & Examples | MathSciBuddy