Question 312210
The general formula for a circle not center at the origin is

(x - h)^2 + (y - k)^2 = r^2

You were given x^2 +(y+5)^2 = 17.

The center is (h,k).  From your equation, I can see that h = 0 and k = -5.

The center is (0,-5).

The radius = r in the general formula for a circle.

r^2 = 17

r = sqrt{17}.

The center is the point (0,-5) and the radius is the square root of 17 written
sqrt{17}.