Aptitude - Question 9

Question

The product of two numbers is 40 and the sum of their squares is 89. 
The difference of the number is:

(A) 5 
(B) 4
(C) 6 
(D) 3

Answer 1

let the number be x and y

xy= 40

x^2 + y^2 = 89

5 and 8 satisfy these equations

difference between number is 3

Answer 2

(a-b)^2 = (a^2 +b^2) - 2*(a*b)

(a-b)^2 = 89 - 2*40

(a-b)^2 = 89 - 80 = 9

So, (a-b) = 3

Ans.: 3