Question

Write the general form of the equation which matches the graph below.

Answer 1

no pic

Answer 2

sorry one second

Answer 3

@pgpilot326

Answer 4

where's the focus? where is the directrix?

from that you should be able to determine the equation.

check out the site: http://www.purplemath.com/modules/parabola.htm

Answer 5

The focus is (3,-4) and the directrix is y = 4. Is that right?

Answer 6

correctamundo!

Answer 7

okay, thank you! I'm having a bit of trouble finding a to plug into the formula though. I know it has to be negative, but I'm not sure how to find out what it would be. I believe (3,0) is the vertex?

Answer 8

yeah, the vertex is (3, 0)
=> 4p(y-k) = (x-h)^2 so 4py=(x-3)^2
p is the distance from the vertex to the directrix so p = 4 in this case.

thus 16y=(x-3)^2 or y = (1/16) (x-3)^2

Answer 9

so it would be 1/16 (x^2 - 6x + 9)?

Answer 10

yeah, but why did you multiply that out? do they want it in ax^2 +bx +c form?

Answer 11

I just looked at the problem and I shouldn't have done that lol sorry about that. so 1/16 is a?

Answer 12

yeah. 4p = 1/a. sorry, but i did make one little goof. since the parabola opens down, p should be negative.

so actually, p = -4, not 4. sorry about that.

Answer 13

it's fine thank you so much!

Answer 14

you're welcome