Identify the center and the radius of the circle with equation (x - 3)2 + (y + 1)2 = 81?

The equation of the circle can be written (x - p)² + (y - q)² = r², where r is the radius and (p,q) is the centre of the circle.
Then, (x - 3)² + (y + 1)² = 9², is the equation of the circle with its centre at (3, -1)and radius 9.