<PRE><B>Question 52470</B>
Find the vertex, focus, and directrix of the parabola x^2-4x-4y+16=0
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Rewrite as x^2-4x+? = 4y+16+?
Complete the square:
x^2-4x+4 = 4y+20
(x-2)^2=4(1)(y+5)
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Vertex at (2,-5).
Since 4p=4, p=1
Focus = (2,-5+1)= (2,-4)
Directrix is y=-5-1=-6

Cheers,
Stan H.
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