x^2+y^2-18y=-17 find radius and center?

Question

X^2 means squared y^2 same thing

Answer 1

For a circle, the formula is:
(x - a)^2 + (y - b)^2 = r^2
where a,b is the center, and r is the radius.

So, we need to get from the given form to the preferred form for a Circle.
x^2 + y^2-18y = -17
x^2 + (y^2 - 18y + 81) - 81 = -17
(x - 0)^2 + (y - 9)^2 = 64 = 8^2

r = 8
center = (0,9)