Answer:
Center: (-1,0)
Radius: [tex]\sqrt{21}[/tex]
Step-by-step explanation:
You can complete the square for x:
[tex]x^2+2x+y^2=20 \\\\(x^2+2x+1)-1+y^2=20 \\\\(x+1)^2+y^2=21[/tex]
The standard form for a circle is [tex](x-h)^2+(y-k)^2=r^2[/tex], where h is the x coordinate of the center of the circle, k is the y coordinate, and r is the radius. Therefore, the center of this circle is at (-1,0), and the radius is [tex]\sqrt{21}[/tex]. Hope this helps!
