Page 35 - 新思维数学活动用书7 样章

2 Expressions, formulae and equations

2 Copy and complete these flow charts to work out the value of x.
a x + 3 = 7 x + 3 7 b x +1 = 9 x + 1 9

x = − 3 7 x = − 1 9

c x + 6 = 11 x + 6 11 d x + 2 = 13 x + 2 13

x = − 11 x = 13

e x + 4 = 12 x + 4 12 f x + 9 = 15 x

x = x =

3 Copy and complete these flow charts to work out the value of x.

a x − 1 = 5 x − 1 5 b x − 3 = 8 x − 3 8

x = + 1 5 x = + 3 8

c x − 2 = 9 x − 2 9 d x − 5 = 12 x − 5 12

x = + 9 x = 12

e x − 10 = 8 x − 10 8 f x − 4 = 5 x

x = x = 12

4 Copy and complete these flow charts to work out the value of y.

a 2y = 6 y × 2 6 b 4y = 8 y × 4 8

y = ÷ 2 6 y = ÷ 4 8

Practice

5 Solve each of these equations. Check your answers by substituting your answer back into the
original equation.
a x + 2 = 6 b x + 6 = 9 c 4 + x = 11 d 15 + x = 21
e x − 5 = 10 f x − 4 = 6 g x − 15 = 12 h 5x = 20
i 3x = 30 j 4x = 28

6 Solve each of these equations. Check your answers by substituting your answer back into the
original equation.
a 14 = x + 3 b 9 = x + 5 c 12 = x − 6
d 20 = x − 5 e 14 = 2x f 50 = 10x

34