Question

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

Answer 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).