If a and b be positive integers such that a2 - b2 = 19, then the value of a is
19
20
9
10
If a and b are two odd positive integers, by which of the following integers is (a4 - b4) always divisible?
3
6
8
12
A drum of kerosene is full. When 30 L of kerosene is drawn from it, it remains full. The capacity of the drum is
120 L
135 L
150 L
180 L
By what least number should 675 be multiplied so as to obtain a perfect cube number?
3
5
24
40
B.
5
675 = 3 x 3 x 3 x 5 x 5
Therefore, 5 should be multiplied by 675.
So, as to obtain a perfect cube number.
Two numbers are in the ratio 3 : 4. Their LCM is 84. The greater number is
21
24
28
84