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).
