Page 22 - 新思维数学活动用书8 样章

2.3 Expanding brackets

4 Copy and complete the boxes to simplify these expressions. Some have been started for you.
a 3(2x + 1) b 5(4x + 9)
× 2x 1 × 4x 9

3 6x 5

3(2x + 1) = 6x + 5(4x + 9) = +
c 2(3y − 7) d 5(8y − 5)
× 3y −7 × 8y −5

2 −14 5

2(3y − 7) = −14 5(8y − 5) = −
5 Expand the brackets.
a 6(a + 6) b 5(b + 7) c 7(c − 8)

d 6(d − 9) e 5(8 + e) f 7(7 + f)
g 6(6 − g) h 5(7 − h)

Practice

6 Expand the brackets.
a 7(8i + 9) b 6(8 + 7j) c 5(6k − 7)
d 7(8 − 9l) e 6(9a + 8m) f 5(7b + 6n)
g 7(7c − 8x) h 6(9px + 8y)

7 Read what Marcus says.

If I expand 4(a − 7)
and 4(7 − a), I will get the
same answer, as both
expressions have exactly the
same terms in them.

Is Marcus correct?
Explain your answer.

8 Expand and simplify each expression. Tip
a 6(a + 7) + 8(a + 9) b 8(b + 7) + 6(5b + 6)
c 7(c + 8) + 9(8 + 7c) d 7(8d + 9) − 8(d + 7) Part d =
e 6(5 + 6e) − 7(8e + 9) f 9(8f + 7g) − 6(5g − 6f) 56d + 63 − 8d − 56
= …

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