Question

Positive number when decreased by 4, is equal to 21 times the reciprocal of the number. the number is select one: a. 3 b. 5 c. 7 d. 9

Answer 1

Answer:

c. 7

Step-by-step explanation:

ATQ;

let the number be 'x' and it's reciprocal is 1/x

Then,

x-4 = 21/x ==> x(x-4) = 21

x^2-4x-21 = 0

x^2-7x+3x-21=0

x(x-7)+3(x-7) = 0

(x-7)(x+3) = 0

x-7=0. or. x+3=0

x=7 or x=-3

Therefore, x=7

option c. 7

Hope! it would help u