Since the directrix is vertical, use the equation of a parabola that opens up or down.

The vertex is halfway between the directrix and focus. Find the coordinate of the vertex using the formula . The coordinate will be the same as the coordinate of the focus.

Simplify the vertex.

Add and .

Divide by .

The distance from the focus to the vertex and from the vertex to the directrix is . Subtract the coordinate of the vertex from the coordinate of the focus to find .

Subtract from .

Substitute in the known values for the variables into the equation .

Simplify.

Find the Parabola with Focus (5,-1) and Directrix y=1 (5,-1) y=1