find the focus of y^2=-5x

Question

find the focus y^2=-5x

Answer 1

5x=-y² is a parabola lying on its side. Also, its arms are extended to the left (negative side) with vertex at (0,0). The focus has the same y coordinate as the vertex. 4fx=-y² where f is the focal length, so 4f=5, f=5/4. The focus has to be to the left of the vertex making the focus (-5/4,0).