Question

If geometric mean between x and y is G, then the value of 1/(G² - x²) + 1/(G²  - y²) is equal to

(A) G²

(B) 1/G²

(C) 2G²

(D) 3/G²

Answer 1

Correct Answer is: (B) 1/G²

G = √xy

∴ 1/(G² - x²) + 1/(G² - y²) = 1/(xy - x²) + 1/(xy - y²)

= 1/(x - y) .[- 1/x + 1/y] = 1/xy = 1/G²