Find the standard equation of the parabola with focus at 4 0

Find the standard equation of the parabola with focus at (-4, 0) and the directrix the line x = 4

Then equate the two distances

(x, y) a point on parabola

distance from focus = distance from directrix

sqrt[(x +4)^2 + y^2] = | x - 4|

(x+4)^2 + y^2 = (x-4)^2

x^2 + 16 +8x + y^2 = x^2 +16 -8x

y^2 +8x = -8x

y ^2 = -16x