Chapter 7, Conic Sections - Section 7.1 - Parabolas - 7.1 Exercises - Page 555: 44

$x^2=-12y$

It is a parabola with vertical axis. Focus: $(0,p)$ Directrix: $y=-p$ $p$ is a negative number because the focus is on the negative x-axis. Distance between the focus and the directrix: $-p-p=-2p$ $-2p=6$ $p=-3$ Equation: $x^2=4py$ $x^2=4(-3)y$ $x^2=-12y$