parabola equation

Question

find the standard form of the equation of the parabola with the given characteristics and vertex at the origin.

Focus (-2,0)

Answer 1

x = ay^2 vertex (0,0), focus (-2,0) directrix x= 2

to find "a" the leading coefficient, plug in any other point, such as (-2,4)

-2 = 16a

a =-1/8

x=(-1/8)y^2