Answer
Center: $(0,-12)$
Radius: $r=2\sqrt 6$
Work Step by Step
The equation of a circle in standard form:
$(x-h)^2+(y-k)^2=r^2$ in which $(h,k)$ is the center and $r$ is the radius
$x^2+(y+12)^2=24$
$(x-0)^2+[y-(-12)]^2=(\sqrt {24})^2$
Center: $(0,-12)$
Radius: $r=\sqrt {24}=2\sqrt 6$
