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Question 647240: find the focus and directrix
show all of your work
9x^2=4y
Answer by aaronwiz(69)   (Show Source):
You can put this solution on YOUR website! Hi, my name is Aaron I am in 10th grade and im in honors trig/pre-calc.
I do not feel like showing all the work, because I have lots of HW to do. However I will guide you, and provide an answer.
First put it in the correct form, (x-h)^2=4p(y-k) we know the vertex is at (0,0) so
it turns out being already in the correct form.
As you can see the coef. of y represents the "4p." Thus 4=4p
Since the graph opens up, and p=1, we know the focus is one unit above the vertex (0,1)
Also since p=1 we know the directrix is one unit below the vertex, y=-1 is the equation for it.
hope I helped
-Aaron
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