Q. Let $P$ be the point (1,0) and $\mathcal{Q}$ a point on the locus of $y^{2} = 8x,\ \$The locus of mid point of P$\mathcal{Q}$ is

A) $x^{2} - 4y + 2 = 0$
B) $x^{2} + 4y + 2 = 0$
C) $y^{2} + 4x + 2 = 0$
D) $y^{2} - 4x + 2 = 0$
Explanation

(d)
The coordinates of $P$ are $(1,\ 0)$. A gerneral point$\ \mathcal{Q}\$on $y^{2} = 8x$ is $\left( 2t^{2},\ 4t \right)$. Let mid point of $P\mathcal{Q}$ is$\ (h,\ k)$
$\therefore 2h = 2t^{2} + 1$ and$\ 2k = 4t\ \Rightarrow \ t = \frac{k}{2}$
$\therefore 2h = \frac{2k^{2}}{4} + 1\ \Rightarrow \ 4h = k^{2} + 2\$
Hence, the locus of $(h,\ k)$ is $y^{2} - 4x + 2 = 0$

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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