#### Answer

$(x-2)^{2}+(y+1)^{2}=9$

#### Work Step by Step

Center $(2,-1);$ radius $3$
The equation of a circle is $(x-h)^{2}+(y-k)^{2}=r^{2}$, where $(h,k)$ is the center of the circle and $r$ is its radius.
Both the center and the radius of the circle are known. Substitute them into the formula to obtain its equation:
$(x-h)^{2}+(y-k)^{2}=r^{2}$
$(x-2)^{2}+[y-(-1)]^{2}=(3)^{2}$
$(x-2)^{2}+(y+1)^{2}=9$