Write Equation of Parabola from a Graph's Directrix and Focus

First, find the vertex of the parabola (if possible). Then you can write a system of equations and solve for the other parameters of the parabolic equation.

(Video) Find the Equation of a Quadratic Function from a Graph

by Mathispower4u

Here's a good video by Mathispower4u showing you how to find the equation of a parabola given its graph.