Question

What is the equation of the directrixfor the following parabola:(x - 1)2 = 12(y + 2)

Answer 1

Given an equation of a parabola;

$\begin{gathered} (x-h)^2=4p(y-k)\text{ } \\ \text{Directrix is y=k-p} \end{gathered}$$\begin{gathered} From\text{ the equation of a parabola;} \\ h=1,k=-2\text{ and p=3} \\ \text{Directrix is} \\ y=-2-3 \\ y=-5 \end{gathered}$