You need to know one thing, that the shortest distance between a point and a line is the distance that is perpendicular to the line.

Since is on the axis, which is already perpendicular to the axis, then the shortest distance from this point to the axis is the distance along the axis, i.e. units.

So that means that the distance between and must also be units.

Therefore .

Simplify this for the equation of your parabola.