In standard form. Find the center, radius, intercepts, and graph the circle. x^2+y^2-4x+18y=-69

Question

Please help? I'm confused with how the x and y numbers are different. Can someone show and explain to me how this problem is done? Thanks.

Answer 1

x2 + y2 - 4x + 18y = -69

⇔ x2 - 4x + 4 + y2 + 18y + 81 = 85 - 69

⇔ x2 - 4x + 4 + y2 + 18y + 81 = 16

⇔ (x2 - 2)^2 + (y + 9)^2 = 4^2

⇒ Center = (2, -9) and radius = 4

Intercepts: x - intercepts: (2, 0), (6, 0)

                    y - intercepts: (0, -23), (-15, 0)

To graph the circle, plot the points above and with your compass open at 4 units and with the pin of the compass at the center, draw the circle passing through the points (2, 0), (6, 0), (0, -23) and (-15, 0).