Find an equation that says thatP = (x, y) is equidistant from F = (2, 0) and the y-axis.
Since you title this "parabola", I suspect you already know the answer. However, the derivation is this:
The distance from (x, y) to (2, 0) is and the distance from the (x, y) to the y-axis is simply x. To be equidistant, we must have
Square both sides and simplify.