Page 43 - 新思维数学学生用书8 样章

2 Expressions, formulae and equations

Exercise 2.3

1 Copy and complete the working.
Expand the brackets.
a 3(x + 4) = 3 × x + 3 × 4 b 8(y − 2) = 8 × y − 8 × 2

= 3x + = 8y −
c 9(3q − 4) = 9 × 3q − 9 × 4
= −
2 Expand each expression.
a 4(x + 6) b 7(z − 2) c 2(a + 8) d 6(3 − 4e)

e 2(2p + 3q) f 9(6t − 2s) g 7(6xy − 2z) h 5(2x + y + 4)
3 Copy and complete the working.
Expand the brackets.

a x(y + 3) = x × y + x × 3 b y(y − 2) = y × y − y × 2
= xy + = y −
2
c p(3 + 4p) = p × 3 + p × 4p d q(6q − 15) = q × 6q − q × 15
= + 4p = −
2
4 Expand each expression.

a y(y + 8) b z(2w − 1) c m(m − 4) d n(2n + 5)
e n(9 − 8n) f a(1 − 3b) g e(2e + 7f) h g(3h + 7g)
i h(2h − 5k) j d(3c − 5e)

Think like a mathematician

5 In pairs or a small group, discuss what Zara and Arun say.

I don’t, I get
When I expand 8dc − 14da,
2d(4c − 7a), I get so one of us
8cd − 14ad. must be wrong!

Do you agree with Arun? Explain your answer.

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