Page 32 - 新思维数学活动用书7 样章

2.4 Expanding brackets

Exercise 2.4

Focus

1 Copy and complete the boxes to work out the answers.
a 5 × 13 b 2 × 38

× 10 3 × 30 8

5 2
5 × 13 = + = 2 × 38 = + =

c 7 × 21 d 4 × 17
× 20 1 × 10 7

7 4

7 × 21 = + = 4 × 17 = + =
2 Simplify these expressions. Tip
a 3 × x b 4 × p c 9 × f d 5 × m 3 × x can be
3 Copy and complete the boxes to simplify these expressions. written simply

The first one has been done for you. as 3x.
a 2(x + 3) b 3(x + 4)

× x 3 × x 4

2 2x 6 3
2(x + 3) = 2x + 6 3(x + 4) = +

c 5(m + 1) d 4(n + 2)
× m 1 × n 2

5 4

5(m + 1) = + 4(n + 2) = +
4 Copy and complete the boxes to simplify these expressions. The first one
has been done for you.
a 3(x − 2) b 5(x − 6)

× x −2 × x −6

3 3x −6 5
3(x − 2) = 3x − 6 5(x − 6) = −

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