Question

What is the equation of a parabola with a vertex at (1, -1) and a directrix y = 4.

Answer 1

@muscrat123

Answer 2

yes

Answer 3

and i do not know this

Answer 4

>.>

Answer 5

hello.

Answer 6

\[(x-h)^2=4p(y-k) \\ \text{ where the vertex is } (h,k) \]

Answer 7

p's sign is based on whether the vertex is above the directrix or below the directrix
if the vertex is above the directrix, then p is positive.
if the vertex is below the directrix, then p is negative.

Answer 8

now the other thing p has going for it ..
is that it is the distance from the vertex to the directrix
(or you can say the distance from the vertex to the focus)

Answer 9

so p tells us two things
not just one

Answer 10

it helps to draw what we are given sometimes...
so the directrix is above the vertex so p is negative
can you tell me how far the directrix is from the vertex