# How do you write an equation for the parabola with vertex (-1,2) and directrix x=-2?

##### 1 Answer

Jun 24, 2018

We need to know the value of

#### Explanation:

Since the vertex is the same distance from both the focus and the directrix, we don't need to know the focus. The vertex is at the x-value of

Before we go any further, we should know that the directrix is always outside of the parabola. Since it's a vertical line and is to the left of the parabola, the graph opens to the right. Here's the standard form for a right-facing parabola:

We can use this to find our scale factor. We know that