Question

Please I need help

Write the equation for a parabola with a focus at (1,-4) and a directrix at x = 2.
X=?

Answer 1

Explanation:

The directrix is a vertical line, so the parabola is horizontal. The focus lies to the left of the directrix, so the parabola opens to the left.

For a left-opening parabola:

x = a(y-k)²+h,

a < 0,

vertex (h,k)

focal length p = 1/|4a|

focus (h-p, k)

directrix: x=h+p

Apply your data

focus (1,-4)

directrix x=2

vertex (1.5,-4).

focal length p = 0.5

a = -1/|4p| = -½

x = -½(y-2)²+ ½