2 x + 6*x - 27 - (x + 9)*(x - a)
x^2 + 6*x - 1*27 - (x + 9)*(x - a)
-27 - 3*x + 9*a + a*x
1*(a - 3)*(x + 9)
(1*(a - 3))*(x + 9)
-27.0 + x^2 + 6.0*x - (9.0 + x)*(x - a)
(-3 + a)*(9 + x)