You can
put this solution on YOUR website!with the equation:

how do I make an equation for a circle

I need to solve for center of circle and radius of circe. Thanks!
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You have to complete the squares of the x and y terms.
Divide thru by 2.

Then add amounts to complete the squares:

Collect terms

So the center is at (2.5,4.5), and the radius is 3*sqrt(3)