Question

Find the standard form of the equation of the parabola with a focus at (0, -2) and a directrix at y = 2.

a. y^2 = -2x

b. y^2 = -8x

c. y= -1/8 x^2

d. y=-1/2 x^2

Answer 1

c

Answer 2

Because the focus point is at yy' axis so the parabola will have the formula \[x^{2}=2py\]
and because the focus point is given by the formula A(0,p/2)
we have: p/2=-2 <=> p=-4
so it will be \[x^{2}=-8y =<=> y=-1/8 x^{2}\]
so it's "c"

Answer 3

okay, i get it! thx for the explanation. :)