Page 29 - 新思维数学活动用书8 样章

2 Expressions, formulae and equations

2 Complete these flow charts to work out the value of x.
a 2x + 1 = 11 x × 2 + 1 11

x = ÷ 2 10 – 1 11

b 5x − 2 = 18 x × 5 – 2 18

x = ÷ 5 + 2 18

c 3(x + 4) = 21 x + 4 × 3 21

x = – 4 ÷ 3 21

d x −= x ÷ 4 – 1 5
15
4
x = 5

3 The diagram shows a rectangle.
3x + 2
y
2 +5 15
26

Complete the workings to find the values of x and y. Tips
3x + 2 = 26 x × 3 + 2 26
The lengths of

the rectangle
x = ÷ 3 – 2 26 are the same, so

3x + 2 = 26.
y += y ÷ 2 + 5 15
515
2 The widths of
the rectangle
y = × 2 – 5 15 are the same, so

y +=
5 15.
2

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