Question

What is the equation of the parabola, in vertex form, with vertex at (2,-4) and directrix y=-6?

x^2=12y

answer choices:
(y+4)^2=-4(x+2)
(x-2)^2=-1/4(y+5)
(x-2)^2=4(y+5)
(y+2)^2=1/4(y+4)

Answer 1

What say you?

(2,-4) implies something that looks like (x-2) an (y - (-4)) = (y+4)

What can we throw out based on that observation?

Answer 2

you lost me with that second half

Answer 3

i think im supposed to convert this to standard form first?
which is
y=x^2 -12

Answer 4

i shouldve included the equation.
x^2=12y

Answer 5

actually i have posted the wrong thing completely, sorry. i will tag you in the next thing

Answer 6

That equation appears to have nothing to do with the question.

Here are the choices.

A: (y+4)^2=-4(x+2)
B: (x-2)^2=-1/4(y+5)
C: (x-2)^2=4(y+5)
D: (y+2)^2=1/4(y+4) <== This makes no sense. 'x' is missing.

If the x-coordinate of the vertex is 2, we must have something that looks like "(x-2)". This eliminates A and D and we are left with two choices

B: (x-2)^2=-1/4(y+5)
C: (x-2)^2=4(y+5)

If the y-coordinate of the vertex is -4, we must have something that looks like "(y+4)". This eliminates B and C and we are left with NO choices.

Either you copied the problem incorrectly or the correct answer is "E: None of the Above". We didn't even use the Directrix information.