Find the center and radius of the circle. If the equation has no graph, state so
. 7. x2 + y2 + 8x + 2y + 18 = 0
10. x² + y2 - 2x + 2y - 3 = 0
8. x + y2 - 6x - 12y = 0
11. x² + y2 - 4x - 4y + 8 = 0
9. x2 + y2 + 6x - 2y + 1 = 0
12. 2x² + 2y2 + 2x + 6y = 3​