Page 10 - 新思维数学活动用书9 样章

1.3 Indices

14 Do these additions. Give your answers in standard form.
a 8.1 × 10 + 9.4 × 10 5 b 6.7 × 10 + 6.7 × 10 7
7
5
c 3.6 × 10 + 2.9 × 10 −5 d 2.86 × 10 + 8.6 × 10 −5
−5
−5

1.3 Indices

Exercise 1.3

Focus

1 Write each number as a fraction.
a 7 −1 b 7 −2 c 5 −3
d 3 −4 e 15 −2 f 20 −2

2 Write these numbers as powers of 4.
a 1 b 1 c 1
4 64
d 256 e 1 f 16 −1
256
3 Write each number as a power of 5.
a 0.2 b 25 c 0.04
d 125 −1 e 15 0
4 Find the value of x when
−3
a x = 2 b x = 3 c x = 5 d x = 10.

Practice

5 Write the answer to each multiplication as a power of 12.

3
a 12 × 12 − 1 b 12 × 12 − 5
4
c 12 − 1 × 12 − 2 d 12 − 4 × 12 7
6 Write the answer to each multiplication in index form.
a 5 × 5 − 1 b 4 − 3 × 4 − 3 c 8 − 6 × 8
4
d 15 × 15 − 5 e 5 − 6 × 5 − 6
5
7 Write the answer to each division as a power of 7.
3
5
a 7 ÷ 7 2 b 7 ÷ 7 4
−
4
4
c 7 ÷ 7 − 2 d 7 ÷ 7 − 3

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