Question

Write the equation in standard form, given the following information.
vertex(-2,4), directrix y=1

Answer 1

well, you know that the equation for a parabola with vertex at (0,0) directrix y = -p is

x^2 = 4py

Your parabola has been shifted so the vertex is at (-2,4), so you want

(x+2)^2 = 4p(y-4)

Your directrix is at y = 1, which is 3 units below the vertex, so p=3

(x+2)^2 = 12(y-4)

see the graph at

http://www.wolframalpha.com/input/?i=parabola+(x%2B2)%5E2+%3D+12(y-4)