SOLUTION: Identify the conic x^2-4y^2-4x-8y-4=0 and find its center and foci

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Question 267239: Identify the conic x^2-4y^2-4x-8y-4=0 and find its center and foci
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
This conic is a hyperbola. The adjusted equation after completing the square is
%28x-2%29%5E2+-+4%28y%2B2%29%5E2+=+4+%2B4%2B4
or
%28x-2%29%5E2%2F12+-+%28y%2B2%29%5E2%2F3+=+1
The center is (2, -2)
The foci are sqrt(12+3) = sqrt(15)
The coordinates of the foci are
(2 +- sqrt(15), -2)