Answer
The center is at $(-2,3)$ and the radius is $4$.
Work Step by Step
The general equation for a circle with radius $r$ and centre $(h,k)$ is: $(x-h)^2+(y-k)^2=r^2$.
$x^2+y^2+4x-6y-3=0\\x^2+4x+4+y^2-6x+9-4-9-3=0\\(x+2)^2+(y-3)^2=4^2$
Hence here the center is at $(-2,3)$ and the radius is $4$.
