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JEE MAIN 2021
25-02-2021 S2
Question
A hyperbola passes through the foci of the ellipse $\frac{x^2}{25}+\frac{y^2}{16}=1$ and its transverse and conjugate axes coincide with major and minor axes of the ellipse, respectively. If the product of their eccentricities in one, then the equation of the hyperbola is :
Select the correct option:
A
$\frac{x^2}{9}-\frac{y^2}{25}=1$
B
$\frac{x^2}{9}-\frac{y^2}{16}=1$
C
$x^2-y^2=9$
D
$\frac{x^2}{9}-\frac{y^2}{4}=1$
✓ Correct! Well done.
✗ Incorrect. Try again or view the solution.
Solution
For ellipse $$ e_1=\sqrt{1-\frac{b^2}{a^2}}=\frac{3}{5} $$ for hyperbola $$ e_2=\frac{5}{3} $$ Let hyperbola be $$ \frac{x^2}{a^2}-\frac{y^2}{b^2}=1 $$ it passes through $(3,0) \Rightarrow \frac{9}{a^2}=1$ $$ \begin{aligned} \Rightarrow \quad & a^2=9 \\ \Rightarrow \quad & b^2=a^2\left(e^2-1\right) \\ & =9\left(\frac{25}{9}-1\right)=16 \end{aligned} $$ ∴ $\quad$ Hyperbola is $$ \frac{x^2}{9}-\frac{y^2}{16}=1 $$
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Question Tags
JEE Main
Mathematics
Easy
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