воскресенье, 2 апреля 2017 г.

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

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