Question

Write an equation of a parabola with a vertex at the origin and a directrix at y=-5.


my answer is focus 6,0, directrix =-6

Answer 1

(x-0)^2 = 4a(y-0)
a = distance vertex to focus or to directrix
if a is +, parabola holds water

here directrix is below vertex, so a is +5

x^2 = 20 y