Question

if one point of a focal chord of a parabola x^2-8y=0 is (-4,2), what will be the other end of the focal chord.

Answer 1

Given: x^2 - 8y = 0. FC(-4,2).

8y = x^2,
y = (1/8)x^2, y-parabola.

h = Xv = -b/2a = 0/2a = 0.
k = Yv = 0^2/8 = 0.

V(h,k) = (0,0).

F(0,y)

V(0,0)

a = 1/8.
4a = 1/2.
1/4a = 2.

y = k + 1/4a = 0 + 2 = 2.

FC = 1/a = 8/1 = 8.

FC: (-4,2), F(0,2), (X2,2).
X2 -(-4) = 8,
X2 + 4 = 8,
X2 = 8-4 = 4.

FC: (-4,2),(4,2).

Answer 2

I think that this answer is wrong