Question

I will give anything :)
Derive the equation of the parabola with a focus at (4, −7) and a directrix of y = −15. Put the equation in standard form.

f(x) = one sixteenthx2 − 8x + 11
f(x) = one sixteenthx2 − 8x − 10
f(x) = one sixteenthx2 − one halfx + 11
f(x) = one sixteenthx2 − one halfx − 10