Lesson 1. Substitution

Letters can be used in place of number to solve problems:

Example – shoes cost £40

                   shoes cost £x

a + b is an algebraic expression

EXAMPLES:

3a means 3 × a

ab means a × b

a² means a × a

^a/_b means 3 ÷ a

a³ means a × a × a

7a + 2 means “7 × a then add 2”

7(a + 2) means “a + 2 then multiply by 7”

4a² means “a × a then multiply by 4”

(4a)² means “4 × a then square the answer”

EXAMPLES:

Find the value of each expression when

a = 3, b = 2 and c = 5

ab = 3 × 2 = 6

c² = 5 × 5 = 25

5a – 1 = 5 × 5 – 1 = 24

4(b + 3) = 4 × (2 + 3) = 4 × 5 = 20

^c/_b = 5 ÷ 2 = 2.5

(3b)² = (3 × 2)² = 6² = 6 × 6 = 36

3b² = 3 × b × b = 3 × 2 × 2 = 12

Lesson 1

•  Test 1 
•  Test 2
•  Test 3