## Intermediate Algebra for College Students (7th Edition)

$(x-2)^2+(y+1)^2=9$
Use standard form of equation of circles; $(x-a)^2+(y-b)^2=r^2$ Here, $r$ defines radius and $(a,b)$ defines center. Then, $x^2+y^2-4x+2y-4=0$ or, $(x^2-4x+4)+(y^2+2y+1)=4+4+1$ or, $(x-2)^2+(y+1)^2=9$