Page 63 - 新思维数学学生用书8 样章

2 Expressions, formulae and equations

Check your progress

1 Jin thinks of a number, x.
Write an expression for the number Jin gets when he divides the number by 2
then adds 5.

2 a Use the formula K = mg to work out K when m = 12 and g = 4 .
b Rearrange the formula K = mg to make m the subject.
c Use your formula in part b to work out m when K = 75 and g = 10.
3 Expand
a x(x + 3)

b 5y(7y − 4w)
4 Factorise
a 6x + 9

b 2y − 12y
2
5 Work out the value of x and y in this diagram.
All measurements are in centimetres.

6(x + 1)

y 20
3 + 16

3x + 21

6 Write the inequality shown by this number line. Use the letter x.

0 5 10 15 20 25

62