Q. The chord joining the points where $x = p$ and $x = q$ on the curve $y = ax^{2} + bx + c$ is parallel to the tangent at the point on the curve whose abscissa is

A) $\frac{p + q}{2}$
B) $\frac{p - q}{2}$
C) $\frac{pq}{2}$
D) None of these
Explanation

(a)
For $x = p,\ y = ap^{2}bp + c$
And for $x = q,\ \ \ y = aq^{2} + bq + c$
Slope $= \frac{aq^{2} + bq + c - ap^{2} - bp - c}{q - p}$
$= a(q + p) + b$
$\frac{dy}{dx} = 2ax + b = a(q + p) + b$
(according to the equation)
$\therefore\ \ \ x = \frac{q + p}{2}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

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