## Precalculus (6th Edition) Blitzer

Focus is: $(-2,0)$ and directrix is: $x-2=0$ See the attached graph.
Standard form of a parabola is given as: $y^2=4px$ ...(1) Formula to find focus is: $F(p,0)$ and formula to find directrix is: $x=-p$ or, $x+p=0$ As we are given that $y^2=-8x \\ or, y^2=4(-2)x$ Compare this form with the equation (1), we have: $p=-2$ Thus, Focus is: $(-2,0)$ and directrix is: $x-2=0$ See the attached graph.