SOLUTION: Could you please help me solve this? find the center (h,k) and radius r of the circle. I have no idea how to work out. x^2+y^2-12x+6y+35=0

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Question 126884: Could you please help me solve this? find the center (h,k) and radius r of the circle. I have no idea how to work out.
x^2+y^2-12x+6y+35=0
Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
Start with the general formula for a circle

Somehow you have to get your equation into that form

Group the x terms together and the y terms together
and subtract from both sides

Now do the operation called completing the square
on the x terms and the y terms
You do that by taking 1/2 of the coefficient of
x (or y), squaring it, then add it to both sides

Notice that this is the exact same equation
I started with because I added the same thing to BOTH sides

Now you can get this into the form

If you just match up the terms, you see that

So, the center is at (6,-3) and the radius is