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1 Laws of Indices: Level 1 Exercise Full Solution

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1

Laws of Indices

Level 1 Exercise Full Solution


1

(a)
(b)
(c)

a 4 a 2 = a 4+ 2 = a6
y 5 y 4 = y 5 4 = y
( y 3 ) 2 = y 32 = y 6

(d)

x 2
x2
x2
)
=
=
y2
y 2 2 y 4

(e)

x7
x7
x 7
) y5 = 7 y5 = 2
y
y
y

(f)

( x 2 y 3 ) ( x3 y 2 )2 = ( x 2 y 3 ) ( x 6 y 4 ) = x 2 6 y 3 4 =

(a)
(b)

4 7 4 7 = 4 7 7 = 4 0 = 1
2 2 2 3 = 2 2( 3 ) = 2 5 = 32

(c)

3 1 3 2 = 3( 1 )+( 2 ) = 3 3 =

(a)

a 4 a 2 = a 42 = a 2

(b)

a 6 a 5 = a 6 5 = a 11 =

1
a11

(c)

( a 2 ) 3 = a ( 2 )3 = a 6 =

1
a6

(d)

a 3 a 2 a 1 = a 3 2 + ( 1 ) = a 6 =

(a)
(b)
(c)
(d)

1
27

35
1
= 35 6 = 3 1 =
6
3
3
4 3
43
(2 )
2
212
=
=
=1
( 2 2 ) 6 2 26 212
( 8 3 ) 2 8 32
1
= 5+ 2 = 8 6 7 = 8 1 =
5
2
8
8 8
8
5 2
7
10 7
3
( 2 ) 2 = 2
=2 =8

Hong Kong Exam & Research

1
a6

1
x4 y

(a)

(b)

3x = 9
3 x = 32
x=2
1
9 x =
27
( 32 ) x =

1
33

3 2 x = 3 3
2x = 3
3
x=
2
(a)

a x 5 = a 4
x5 = 4
x=9

(b)

a3x = a9
3x = 9
x=3

(a)
(b)

8 10 2 = 800
6.3 103 = 6300

(a)
(b)

5 10 2 = 0.05
7.5 10 3 = 0.0075

(a)
(b)

8000 = 8 103
0.074 = 7.4 10 2

10

(a)

5 3 =

(b)

13
1
1
= 3 =
27
3
3

1
1
=
3
125
5

Hong Kong Exam & Research

Level 2 Exercise Full Solution


11

12

13

(a)

52 ( 22 )3 42 = 52 223 2 2 = 52 22 = 100

(b)

9 2 3 = 3 4 +1 = 3 3 =

(c)

(d)

3 2 ( 42 190 ) = 3 2 42 =

(a)

3x 2 4( x 2 ) 3 2 ( x 3 ) 3 = 3x 2 4 x 6 2 x 9 = 24 x 17

(b)

( 3a 2 ) 2 ( 6a 4 )3 32 a 4 63 a12 9 216 4 +12 6


=
=
a
= 6a10
3 2
2 6
( 18a )
18 a
324

(a)

( 4 2 b 6 )( 2 3 b 3 ) 2 = ( 2 4 b 6 )( 2 6 b 6 ) = 2 2 = 4

(b)

( a 2b 2 )3
a 6b 6
b9
8 9
a
b
=
=
=
( a 2b 3 ) 1 a 2b 3
a8

(c)

4a 2 b 3 ( 2abc 3 ) = 4a 2 b 3 4a 2 b 2 c 6 =

(d)

a3 b3
2 2
b a

1
27

3 0
5
5
5
125
) ( ) 3 = 1 ( ) 3 = ( )3 =
5
3
3
3
27

16
9

4a 2 b 3
1
= 5 6
2 2 6
4a b c
b c

a 6 b 3 a 6 a 2 a 62 a 4

=
=
b
b 4 a 2 b 4 b 3 b 4 3

(e)
( a 10 bc 20 ) 0 ( a 3 b 2 ) 3 = 1 a 3( 3 ) b ( 2 )( 3 )
= 1 a 9b 6
1
= 9 6
a b
a9
= 6
b

(f)

( 6a 2 b 5 ) 2 ( 2a ) 3 ( 3b 2 ) 2 = 36a 4 b10 ( 8a 3 9b 4 )
36a 4 b10
72a 3b 4
1
= a 43 b10 4
2
a 7b6
=
2
6
b
= 7
2a
=

Hong Kong Exam & Research

14

(a)

10 x = 0.01 =

1
1
= 2 = 10 2
100 10

x=2
(b)

32 x =

1
1
1
= 3 4 = 12 = 3 12
4
27
(3 )
3

2 x = 12
x=6
15

2 x + 2 2 x = 48
2 x 2 2 2 x = 48
2 x ( 4 1 ) = 48
3( 2 x ) = 48
2 x = 16
2 x = 24
x=4

16

4.9 107 8.3 109 = 4.9 8.3 107 + 9 = 40.67 1016 = 4.067 1017

17

Number of seconds in a week


= 7 24 60 60
= 604800
= 6.048 10 5

Hong Kong Exam & Research

MC Exercise Full Solution


1

A
Number of minutes = 60 24 9 = 12960 = 1.296 10 4

B
p1
1
=
q
pq

(1)

p1 q =

(1) is not true

(2)

p

q

(3)

(2) is true
p 0 q 0 = 1 1 = 1

(3) is not true

p 3
= p 3q 3
q 3

C
2 4 4 2 = 2 4 ( 2 2 ) 2 = 2 4 2 4 = 2 4+ 4 = 2 8

A
9 2 a = 3b
( 3 2 ) 2 a = 3b
3 4 a = 3b
4a = b
b
4
a 1
=
b 4

a=

C
3 n +1 + 3 n 1 3 n 3 + 3 n 3 1
=
3 n 1
3n 3 1
1
3n ( 3 + )
3
=
1
n
3
3
10 1
=

3 3
= 10

Hong Kong Exam & Research

0.157 = 1.57 10 2 x
1.57 10 1 = 1.57 10 2 x
1 = 2x
x=

1
2

Hong Kong Exam & Research

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