JEE Main2012MathematicsHyperbolaActual
If the eccentricity of a hyperbola x^2 9 - y^2 b^2 =1 , which passes through (K, 2) , is 13 3 , then the value of K^2 is
Options
- A18
- B8
- C1
- D2
Correct answer
A. 18
Step-by-step solution
Given hyperbola is x^2 9 - y^2 b^2 =1 Since this passes through (K, 2) , therefore K^2 9 - 4 b^2 =1 Also, given e= 1+ b^2 a^2 = 13 3 aligned & 1+ b^2 9 = 13 3 9+b^2=13 & b= 2 aligned Now, from eq ^ n (1), we have aligned & K^2 9 - 4 4 =1 ( b= 2) & K^2=18 aligned