Let a and b respectively be the semitransverse and semi-conjugate axes of a hyperbola whose eccentricity satisfies the equation 9e2−18e+5=0. If S(5, 0) is a focus and 5x=9 is the corresponding directrix of this hyperbola, then a2−b2 is equal to :
7
-7
5
-5
As we learnt in
Equation of directrices -
- wherein
For the Hyperbola
or
for Hyperbola
Also
Also,
Option 1)
7
Incorrect
Option 2)
-7
Correct
Option 3)
5
Incorrect
Option 4)
-5
Incorrect
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