In this form, ( h, k) is the center of the circle and r is its radius. Now, let's consider the following diagram.
We can see from the diagram that the center of the circle is ( 4, - 1) and its radius is 3.
This information is enough to write the equation.
(x- 4)^2+(y-( - 1))^2= 3^2
⇕
(x-4)^2+(y+1)^2=9
