<PRE><B>Question 182142</B>
Give the center and radius of the circle {{{x^2+y^2+6x-8y-56=0}}}

I think the center is (3,4) but I wasn&#39;t sure about the radius. I would appreciate any step by step help.
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x^2+y^2+6x-8y-56=0
Complete the square on the x and on the y terms to get:

x^2 + 6x + ? + y^2 - 8y + ? = 56 + ?

x^2 + 6x + 9 + y ^2 - 8y + 16 = 56 + 9 + 16

(x+3)^2 + (y-4)^2 = 81
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Center is (-3,4); radius = sqrt(81) = 9
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Cheers,
Stan H.
 

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