SOLUTION: Find the length of the radius of a circle whose equation is 2x^2+2y^2-12x+4y-15=0

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Question 1083974: Find the length of the radius of a circle whose equation is 2x^2+2y^2-12x+4y-15=0
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
2x%5E2%2B2y%5E2-12x%2B4y-15=0
x%5E2%2By%5E2-6x%2B2y-15%2F2=0
%28x%5E2-6x%29%2B%28y%5E2%2B2y%29=15%2F2
%28x%5E2-6x%2B9%29%2B%28y%5E2%2B2y%2B1%29=15%2F2%2B9%2B1
%28x-3%29%5E2%2B%28y%2B1%29%5E2=15%2F2%2B18%2F2%2B2%2F2
%28x-3%29%5E2%2B%28y%2B1%29%5E2=35%2F2
So the circle is centered at (3,-1) and has a radius,
R%5E2=35%2F2
R=sqrt%2835%2F2%29
R=sqrt%2870%29%2F2