If a vertex is (3,0) and focus at (3,-2), what is the equation of the parabola?

Question

anonymous · Answer

is it $$(x-3)^{2} =8y$$
or $$(x-3)^{2} =-8y$$

tkhunny · Answer

Well, if it is "+", how is it going to go down around that focus?

anonymous · Answer

|dw:1366185261951:dw|

anonymous · Answer

$$ \text{Okay if you don't believe me Let's work backwards  }\ (x-3)^2=8y\  y=   \frac{(x-3)^2}{8}\  y=a(x-h)^2+k  \      \  \  Focus=(3,2) \  \ \   \   Directrix: y=-2  , \   Vertex: (3,0),  \  \   Axis\ \ \  of\ \  Symmetry: x=3$$

anonymous · Answer

Got it Thanks!
I had gotten positive, but my friend's note said negative, So i was a bit confused.. and then I thought that the parabola had to be graphed upwards in order to overlap with the focus.. 

Since the graph looks like that, I thought it had to include the focus point of (3,-2)

anonymous · Answer

you did well.  :)