
Yefim S. answered 04/12/21
Math Tutor with Experience
A. y2 - 12x + 18y + 153 = 0; y2 + 18y + 81 = 12x - 72
(y + 9)2 = 12(x - 6)
This is horizontal parabola with vertex at point (6, - 9) and 4p = 12; p = 3. So focus at point (9, - 9).
B. x2 + y2 - 8x - 6y - 39 = 0; ( x - 4)2 + (y - 3)2 - 16 - 9 - 39 = 0; (x - 4)2 + (y - 3)2 = 64.
So, this is circle with center at (4, 3) and radius 8