Question

Write an equation of a parabola with its vertex at the origin and its directrix at y = –2.

Answer 1

\[y =a(x-h)^{2} +k\]
equation for directrix
\[y = k -\frac{1}{4a}\]
h=0
k=0
solve for a

Answer 2

is it -2y^2

Answer 3

???

Answer 4

plug in -2 for y
\[-2 = -\frac{1}{4a}\]

Answer 5

A.) y=1/8y^2
B.) x=-2y^2
C.) x=1/8x^2
D.) y=8x^2

Answer 6

A ??

Answer 7

thats what i got is it right?

Answer 8

this is the y=x^2 type because your directrix is horizontal. the distance from vertex to directrix is 2 so a=2. since your vertex is at the origin, your equation should be y=(1/8)x^2

Answer 9

yes