Answer
$x^{2}=-12 y$
Work Step by Step
Given: Focus: $F(0,-3)$
This gives: $p=-3$
The general form of the equation of a parabola which opens upwards is
$x^{2}= 4py$
Thus, the equation of the parabola becomes:
$x^{2}= (4)(-3)(y)$
$\implies x^{2}=-12 y$
