JEE Main20252 Apr 2025Morning ShiftMathematicsHyperbolaActual
Let one focus of the hyperbola H : x ^2 a ^2 - y ^2 ~b ^2 =1 be at ( 10 , 0) and the corresponding directrix be x = 9 10 . If e and l respectively are the eccentricity and the length of the latus rectum of H , then 9 ( e ^2+l ) is equal to:
Options
- A14
- B15
- C16
- D12
Correct answer
C. 16
Step-by-step solution
aligned & ae = 10 and a e = 9 10 & a ^2=9 and e = 10 3 & Now aligned & ( ae )^2= a ^2+ b ^2 & 10=9+ b ^2 ~b ^2=1 & & = 2 ~b ^2 a = 2(1) 3 & 9 ( e ^2+ ) & =9 ( 10 9 + 2 3 ) & =10+6 & =16 aligned aligned