Question

What is the equation of the directrix of the parabola given by the equation y2 = -24x?

Answer 1

Since y is the suqraed term, it opens left or right
in this form it is
(y-k)²=4p(x-h)

(h,k) is the vertex
if p is negative then it opens to the left and directix is to the right of the vertex
if p is positve then it opens to the right and directix is to the left of the vertex
p is the distance from vertex to directix


so
(y-0)²=4(-6)(x-0)
the vertex is (0,0)
-6 is negative
so
vertex is (0,0)
directix is 6 unts to the right of (0,0) or at x=6

the directix is x=6