Question

If a chord of the parabola $y^2=16x$ has the equation 2x + y = p and midpoint (h, k), than K =

• A. 4
• B. 2
• C. -2
• D. -4

Answer 1

The correct option is D -4

$y^2=16x$, midpoint of chord = (h, k)
equation of the chord is $S_1=S_{11}$
$\Rightarrow 8x-ky+(k^2-16h)=0$ ... (1)
$2x+y-p=0$ ...(2)
(1), (2) represent same line $\Rightarrow$ k = - 4.