Question

What is the directrix of the parabola defined by 1/4(y 3)=(x-2)^2?

Answer 1

For
(x-h)^2=4p(y-k)
vertex=(h,k)
p=vertical distance from vertex to directix
when p is negative, the directix is above the vertex
when p is positive, the directix is below the vertex

(x-2)^2=1/4(y+3)
(x-2)^2=4(1/16)(y+3)
p=1/16
it's positive so we know directix is below vertex
vertex is (2,-3)
go 1/16 down
-3-1/16=-48/16-1/16=-49/16
directix is y=-49/16 aka y=-3.0625