Question

Write the equation of a parabola with its vertex at the origin and directrix at y = 1.

x2 = y

y2 = x

x2 = –4y

y2 = –4x

Answer 1

the answer is option c

Explanation:

Answer 2

Explanation:

The directrix equation is y = k-p and vertex (h,k)

Standard equation parabola is

(x-h)^2 = 4p(y-k)

where (h,k) is vertex and p directed distance from vertex to focus.

(h,k) = (0,0)

Directrix equation is y = k-p

Substitute the y and k values.

1 = 0-p

p = -1

Substitute p= -1 and (h,k) = (0,0) in

(x-h)^2 = 4p(y-k)

x^2 = -4y

Parabola equation is x^2 = -4y.

Hope it helps!!!