Question

What is the directrix of x^2-28y?

Answer 1

where is the equal sign?

Answer 2

Let me check again

Answer 3

Oh oops the minus is supposed to be an equal sign.

Answer 4

@jim_thompson5910

Answer 5

so it's x^2 = 28y ?

Answer 6

Yes

Answer 7

x^2 = 28y

(x-0)^2 = 4*7(y-0)

which is in the form

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

so the focal distance is p = 7 units

Answer 8

the vertex is (0,0), so this means that the directrix is y = -7 since you go down 7 units

you go down 7 units because this is a parabola that opens upward

Answer 9

Thanks! :)

Answer 10

yw