y = A*x^2 + B*x + C
y' = 2*A*x + B
y'' = 2*A
2*A - 2*A*x - B - 6*(A*x^2 + B*x + C) = x^2
-6*A*x^2 + ( -2*A - 6*B )*x + (2*A - B - C) = x^2