Question 197965: find the focus and the directrix of the parabola.the vertex of the parabola is (0,0),i need help because i dont understand where to start persay
y= -1/20x^2
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! find the focus and the directrix of the parabola.the vertex of the parabola is (0,0),i need help because i dont understand where to start persay
y= -1/20x^2
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Put the equation into the form (x-h)^2 = 4p(y-k)
(x-0)^2 = -20(y-0)
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(h,k) = (0,0)
4p = -20
p = -5
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Vertex is at (h,k) = (0,0)
Directrix is y = k-p = 0+5 = 5
Focus is at (h,k+p) = (0,-5)
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Cheers,
Stan H.
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