Find the area of the region satisfying the inequality x^2 + y^2 <= 4x + 6y + 13 - 2x + 8y + 15.
x^2 + y^2 <= 4x + 6y + 13 - 2x + 8y + 15
Rewrite as
x^2 -2x + y^2 - 14y ≤ 28 complete the square on x and y
x^2 -2x + 1 + y^2 -14y + 49 ≤ 28 + 1 + 49
(x - 1)^2 + (y - 7)^2 ≤ 78
This is a circle centered at (1, 7) with a radius^2 of 78
The area lies within the circle and = 78pi units^2