If a chord, which is not a tangent, of the parabola y 2 = 16 x has the equation 2 x + y = p , and midpoint…

If a chord, which is not a tangent, of the parabola y2=16x has the equation 2x+y=p, and midpoint (h, k), then which of the following is (are) possible value(s) of p,h and k?
 
  1. p=-2, h=2, k=-4
  2. p=5, h=4, k=-3
  3. p=-1, h=1, k=-3
  4. p=2, h=3, k=-4

Solution

Equation of chord with mid point (h, k):

k.y-16x+h2=k2-16h

8x-ky+k2-8h=0 

Comparing with  2x+y-p=0, we get

k=-4;2h-p=4

Only p=2, h=3, k=-4 satisfies above relation.

Asked in: JEE Advanced 2017 (Paper 1)

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