Page 79 - ICSE Math 7

0
(b) For what value of a, a = 1 does not hold?
3 –4
(i) 0 (ii) 1 (iii) (iv)
4 3
(c) Which of the following is the prime factorization of 2,160?
4
2
4
3
4
3
3
3
(i) 2 × 3 (ii) 2 × 3 (iii) 2 × 3 × 5 (iv) 2 × 3 × 5
2
–2
n
(d) For what value of n, 2 .2 = 2 ?
(i) 2 (ii) –2 (iii) 4 (iv) 0
(e) Which of the following is the standard form of 2,839?
1
3
2
(i) 283.9 × 10 (ii) 28.39 × 10 (iii) 2.839 × 10 (iv) 0.2839 × 10 4
2. Write True or False.
7
(a) In 3 , the exponent is 3.
8
2
(b) The value of 8 is greater than 2 .
(c) To multiply two numbers in scientific form we can reorder and regroup powers having like
bases.
14
17
97
(d) The value of the expression 3 . 3 – 3 100 . 3 is equal to 1.
 a  −1 b
(e)   = where a, b are non-zero rational numbers.
 b  a
3. Fill in the blanks.
5
(a) The number 2 has base __________ and exponent __________.
(b) The number 343 is 7 raised to the power __________.
(c) When a negative number is raised to an odd power the result is __________ in sign.
n
n
(d) For any natural number n, a = b is possible if, and only if __________.
0
0
0
(e) The value of the expression 1 + (10) + (100) is __________.
n
0
(f) If (200) = 5 , then the value of n is __________.
3 3
2 4
(g) The simplest form of (a ) ÷ (a ) is __________.
n
(h) The scientific or standard form of a number is of the type k × 10 , where k is greater than or
equal to __________ and less than __________.
PRACTICE TIME
1. Express each of the following as a positive power of a number.
2 3
3
3 4
2 2
3
2 4
(a) (15 ) ÷ 15 (b) (10 ) ÷ (100) (c) (a ) × {a ÷ (a ) }
5
 x  3
4
2
2
5
(d) 3 × 27 × 3 (e) (5 × 25 ) ÷ 5 4 (f)  x 
8 

2. Evaluate the following.
3
–4
2 × 9 × 2 5  3  − 2  81    − 3
–2
0
–1
×
(a) 3 + 3 + 3 + 3 –3 (b) (c)   ×    
–3
2
3 × 4 2  5   25   
8
2 × 3 8   2 − 3  9 − 2    3 × 2 2  0
3
–1
0
–3
–2
(d) (e) (3 + 3 ) (2 – 2 ) (f)    ×    ×   2  × 18 ( ) 
5
3
16    3   4     2 × 3  

4 –2
–3 3
(x ) × (y )
3. Find the value of when x = 2 and y = 5.
–4
x × y –12
65