Question

Find the standard form of the equation of the parabola with a focus at (-7, 0) and a directrix at x = 7.

a) x = negative 1 divided by 28y^2
b) -28y = x^2
c) y^2 = -14x
d) y = negative 1 divided by 28x^2

Answer 1

y^2 = -28x.

Explanation:

The general form for this type of parabola is y^2 = 4ax where the focus is at (a,0) and the directrix is x = -a.

So substituting we get

y^2 = 4 * -7 * x

y^2 = -28x

Answer 2

x = 1/(4p)*y^2

x = 1/(4*-7)*y^2

x = -1/28*y^2