SOLUTION: Which of the following is the radius for the circle whose equation is x^2+6x+y^2-8y=-9? thanks for your help.

Question 202357: Which of the following is the radius for the circle whose equation is x^2+6x+y^2-8y=-9? thanks for your help.
Answer by vleith(2983) (Show Source): You can put this solution on YOUR website!
You need to get this equation into the standard form for a circle
So you need to complete the squares for both x and y in your equation and see what comes from that

So r^2 = 16 --> r=4. Center is at (h,k) = (-3,4)
Here is a plot --> http://www30.wolframalpha.com/input/?i=x^2%2B6x%2By^2-8y%3D-9
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