Center and Radius Detective
For [math]x^2+y^2+Dx+Ey+F=0[/math], explain why the center is [math]\left(-\frac{D}{2},-\frac{E}{2}\right).[/math] Then derive an expresison for the radius.
Determine the center and radius of [math]x^2+y^2+10x-4y+13=0.[/math]. Verify that the radius is positive before graphing.