Page 93 - Start Up Mathematics_7

n
2. In exponential form p , p is called the base and n the exponent or the power.
3. Numbers in exponential form obey certain laws. When a and b are non-zero rational numbers
and m and n are whole numbers, we have
n
n
m
m n
m
m
m
(a) a . a = a m + n (b) a ÷ a = a m – n (c) (a ) = a mn (d) a × b = (ab) m
0
m
m
–m
(e) a ÷ b = a m (f) a = 1 (g) a = 1
b a m
n
4. Scientific notation or standard form of a number is of the form p × 10 , where p is a
terminating decimal greater than or equal to 1 and less than 10, i.e., 1 ≤ p < 10. Very large
or very small numbers can be conveniently written in this form.
Review Exercises
Multiple ChoiCe Questions
3 2
1. The expression (5 ) is equal to:
5
9
6
(a) 5 (b) 5 (c) 5 (d) (15) 2
0
2. The law a = 1 does not hold when a equals:
3 –4
(a) 0 (b) 1 (c) (d)
4 3
3. The number 2,160 expressed as product of prime factors is:

2
4
3
3
3
4
3
4
(a) 2 × 3 (b) 2 × 3 (c) 2 × 3 × 5 (d) 2 × 3 × 5
a n a n
4. The law n = does not hold when:
b b 2 –3
(a) a = 2, b = 3 (b) a = , b = (c) n = 0 (d) b = 0
5 5
–2
2
n
5. If 2 . 2 = 2 , then the value of n is:
(a) 2 (b) –2 (c) 4 (d) 0
() (27 5 - ) 1 , 1 771
6. The simplified form of the expression is:
()9 7
(a) 3 (b) –3 (c) 279 (d) –1
81
7. The standard form of the number 2,839 is:
3
2
1
(a) 283.9 × 10 (b) 28.39 × 10 (c) 2.839 × 10 (d) 0.2839 × 10 4
solve Mentally
True or False
7
1. In 3 , the exponent is 3.
8
2
2. The value of 8 is greater than 2 .
3. To multiply two numbers in scientific form we can reorder and regroup powers having like
bases.
17
97
14
4. The value of the expression 3 . 3 – 3 100 . 3 is equal to 1.
a –1 b
5. = where a, b are non-zero rational numbers.
b a

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