Page 25 - 新思维数学活动用书8 样章

2 Expressions, formulae and equations

15 Fill in the missing numbers and letters in these expressions.
Use all the numbers and letters from the cloud. 1 2 5
a 4(3x + ) = x + 28 b 3x(2x − ) = 6 − 3x 7 8 11

c 6( − 3) = 30x − d x(9 − ) = 45x − 5x 2 12 18 x

e 2( x + 4) + 3(4x − ) = 16x − 16 2x 5x x 2
f x(4x + 1) − (x − 5) = 2x + x
2

2.4 Factorising

Exercise 2.4 Key words

factorisations
Focus

When you factorise an expression, you do the opposite to expanding factorise
a bracket. term
Expanding: 3(x + 8) = 3x + 24 Factorising: 3x + 24 = 3(x + 8)

1 Expand these brackets. Use the boxes to help if you want to.
The first one is done for you.
a 2(x + 6) b 3(x + 5)

× x 6 × x 5
2 2x 12 3

2(x + 6) = 2x + 12 3(x + 5) = +

c 5(y − 3) d 4(y − 7)
× y −3 × y −7

5 4

5(y − 3) = − 4(y − 7) = −

2 Factorise these expressions. Use your answers to Question 1.
The first one is done for you.
a 2 x + 12 = 2(x + 6) b 3 x + 15 =

c 5y − 15 = d 4y − 28 =

24