Page 53 - 新思维数学学生用书7 样章

2 Expressions, formulae and equations

6 This is part of Steffan’s homework.

Question

Solve these equations.
a x + 7 = −2 b x – 6 = −2 c 5x = −35
Solution

a x + 7 = −2 b x − 6 = −2 c 5x = −35
x = −2 −7 x = −2 −6 x = −35
x = −5 x = −8 5
x = 7

Mark Steffan’s homework. If he has made any mistakes, explain the mistakes and work out the

correct answers.
7 Solve each of these equations and check your answers.
a 2a + 3 = 13 b 4a + 1 = 17 c 3a – 2 = 13

d 4 = 2c − 8 e 14 = 3c + 2 f 29 = 4c – 3

Think like a mathematician

8 In pairs or groups, discuss how you could answer this question.

The total length of each set of bricks is shown.
a Write an equation involving the lengths of the bricks.
i a cm a cm 8cm

20 cm

ii b cm b cm bcm 3cm

24 cm
b Solve your equations to find the lengths of the bricks.
c Compare your equations and answers with those of other groups and

discuss any differences. How could you improve your work?

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