2 2 y - 12*x + x
y^2 - 12*x + x^2
2 2 x + y - 12*x
x^2 + y^2 - 12*x
/ _________\ / _________\ | / 2 | | / 2 | \x + -6 + \/ 36 - y /*\x + -6 - \/ 36 - y /
(x - 6 + sqrt(36 - y^2))*(x - 6 - sqrt(36 - y^2))
x^2 + y^2 - 12.0*x