Answer:
Explanation:
We have that the focus is at (p,0) and that the directrix is x=-p. Take the point (-p,0) of the directrix. We know that the vertex of the parabola is at the middle point ot the line segment that joins the points (p,0) and (-p,0). To get the middle piont, we take the average coordinate by coordinate. That is, the middle point is
. The general formula of a parabola of vertex (h,k) that opens to the right or to the left is given by
![(y-k)^2 = 4p(x-h)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/drzda4jg8n3u1wbfp939gtepswt3qh9yo9.png)
Where |p| is the distance from the focus to the vertex. If the parabola opens to the right, then p>0 and p<0 otherwise. In our case, h =0=k, so we get that
![y^2 = 4px](https://img.qammunity.org/2021/formulas/mathematics/middle-school/f626nep86849mjnjkd06lurkif9kc63aez.png)