# Center and radius of a circle?

• Dec 28th 2007, 12:21 PM
lemon301
Center and radius of a circle?
How do I find the radius and center of the circle x^2 + 4x + y^2 = 5?
• Dec 28th 2007, 12:26 PM
galactus
Complete the square.

$x^{2}+4x+4=(x+2)^{2}$

$(x+2)^{2}+(y-0)^{2}=9$

The circle is centered at (-2,0) and has radius 3. See?.