A Positive number, when decreased by 4, is equal to 21 times of the reciprocal of the number find the numbers
Soln Date / Update:-22-Jul-2025 04:08PM
Solution:-
Exercise - 2 (A) Q-29.
A Positive number, when decreased by 4, is equal to 21 times of the reciprocal of the number find the numbers.
(A) 3 (B) 5
(C) 7 (D) 9
Soln:-
Let the number = x
A/Q, x - 4 = 21 * 1 / x
Or x ( x - 4 ) = 21
Or x2 - 4x = 21
Or x2 - 4x - 21 = 0
x2 - 7x + 3x - 21 = 0
x ( x - 7 ) +3 ( x - 7 ) = 0
( x - 7 ) ( x + 3 ) = 0
x - 7 = 0 x + 3 = 0
x = 7 x = -3
Positive no. = 7 Ans.
