Q. If the circle $x^{2} + y^{2} = a^{2}$ intersects the hyperbola $xy = c^{2}$ in four points $\left( x_{i},\ y_{i} \right),$ for $i = 1,2,3$ and 4, then $y_{1} + y_{2} + y_{3} + y_{4}\$ equals

A) 0
B) $c$
C) $a$
D) $c^{4}$
Explanation

(a)
Given, $x^{2}y^{2} = c^{4}$
$\Rightarrow \ y^{2}\left( a^{2} - y^{2} \right) = c^{4}$
$\Rightarrow \ y^{4} - a^{2}y^{2} + c^{4} = 0$
Let $y_{1},y_{2},y_{3}$ and $y_{4}\$ are the roots
$\therefore\ y_{1} + y_{2} + y_{3} + y_{4} = 0$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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