Find the center of the circle whose equation is x² - 10x + y² - 10y = - 1 A) (5,5) B) (10,10) C) (10,1)

You need to complete the square and then flip the signs and you'll have your answer:

(x - 5) ² - 25 + (y - 5) ² - 25 = - 1

(x - 5) ² + (y - 5) ² - 50 = - 1

(x - 5) ² + (y - 5) ² = 49

x = 5, y = 5

Therefore your answer is (5,5).

The radius is also the square root of whatever the equation is equal to (root 49 = 7).