Find the center and radius of the sphere for x^2 + y^2 + z^2 - 4x + 8y + 6z + 4 = 0
+36916 "complete the square' for x y and z
x^2-4x + y^2+8y + z^2 +6z = 4
(x-2)^2 + (y+4)^2 + (z+3)^2 = 4 + 4 + 16 + 9
center is thus 2, -4, -3 radius = sqrt (4+4+16+9) = sqrt 33
