Question

If 2x+y+a = 0 is a focal chord of the paraboal y^2+8x=0, then a is

Answer 1

y² = -8x is the equation of parabola
y²= 4(-2)x

hence , focus of parabola, is ( -2, 0)

focal chord is line sigment passing through , focus .

so, put ( -2, 0) in 2x + y + a = 0

2(-2) + 0 + a = 0

a = 4 ( answer )