## If e and e1 are the eccentricities of the hyperbola xy = c^2 and x^2 – y^2 = c^2, then

Q: If e and e1 are the eccentricities of the hyperbola xy = c2 and x2 – y2 = c2, then e2 + e12 is equal to

(A) 1

(B) 4

(C) 6

(D) 8

Ans: (B)
Sol: e = √2 , e1 = √2

⇒ e2 + e12 = 4.

Hence (B) is the correct answer.

## The eccentricity of conic 9x^2 – 16y^2 = 144 is

Q: The eccentricity of conic 9x2 – 16y2 = 144 is

(A) 4/5

(B) 5/4

(C) 4/3

(D) √7

Sol: Hyperbola is $\large \frac{x^2}{16} – \frac{y^2}{9} = 1$