Question

What are the center and radius of the circle with equation `(x-3)^2 + (y+1)^2=16`?

Answer 1

Center: `(3,-1)`.

Radius: `4`

Explanation:

This equation is already written in the "center-radius" form: in fact, if the center `(x_0,y_0)` and the radius `r` are known, then the equation of the cirle is

`(x-x_0)^2 + (y-y_0)^2 = r^2`

So, in your case, the center is `(3,-1)`, and the radius is `sqrt(16)=4`