## Precalculus (6th Edition) Blitzer

$(x-2)^2=-8(y+3)$
General form of a vertical parabola is given as: $(x-h)^2=4p(y-k)$...(1) Here, $\text{Vertex}=(h,k)$ and focus is: $(h, k+p)$ As we are given $\text{Vertex}=(2,-3)$ and focus is: $(2,-5)$ Thus, $h=2,k=-3$ and $k+p=-5 \implies -3+p=-5$ or, $p=-2$ From equation (1), we have $(x-2)^2=4(-2)(y-(-3))$ or, $(x-2)^2=-8(y+3)$