Question

Part a) Write the equation of the circle by completing the square.

Part b) What is the center and the radius of the circle?

x2 + 4x + y2 - 2y = 20

Answer 1

hello :
x² + 4x + y²- 2y = 20

x² + 4x+4-4 + y²- 2y+1-1 = 20
(x² + 4x+4)-4 + (y²- 2y+1)-1 = 20
(x+2)² + (y-1)² = 5²
the radius is : 5      the center: (-2,1)