## Calculus (3rd Edition)

$$x= \frac{1}{8}y^2 .$$
The focus is at $(2,0)$ and the directrix is $x=-2=-c$, hence $c=2$. The parabola is horizontal, opens to the right, and has the equation $$x=\frac{1}{4c}y^2=\frac{1}{8}y^2 .$$