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