What is the equation of the quadratic graph with a focus of (3, 4) and a directrix of y = 8?

f(x) = −one eighth (x − 3)2 + 4

f(x) = −one eighth (x − 3)2 + 6

f(x) = one eighth (x − 3)2 + 4

f(x) = one eighth (x − 3)2 + 6

Question

What is the equation of the quadratic graph with a focus of (3, 4) and a directrix of y = 8?

 f(x) = −one eighth (x − 3)2 + 4

 f(x) = −one eighth (x − 3)2 + 6

 f(x) = one eighth (x − 3)2 + 4

 f(x) = one eighth (x − 3)2 + 6

jenniferjuice · Answer

@IMStuck non free medal here ^.^

imstuck · Answer

lol!!!!!!!

imstuck · Answer

Center is at (3,6)

imstuck · Answer

And this is a negative parabola, meaning it opens downward, becuase the focus is below the directrix.  SO...

jenniferjuice · Answer

Sooooooooo

imstuck · Answer

It's the second choice down.

imstuck · Answer

y = 4px^2 and p = -1/2

imstuck · Answer

4p=-2 so p = -1/2.  Do you see that part?  that's the tricky part of this

jenniferjuice · Answer

i see it

imstuck · Answer

TY for the non-free medal!  Been a pleasure!  I love these things, as ridiculously tedious and difficult as they are!

jenniferjuice · Answer

please help with the other question i tagged you in!?

imstuck · Answer

p is the number of units that the focus is away from the center. The focus is down 2 units so x = -2...4p=-2 and p = -1/2