(2*a + 1)*(a + 1)
1*(a + 1)*(a + 1/2)
(1*(a + 1))*(a + 1/2)
(1.0 + a)*(1.0 + 2.0*a)
2 1 + 2*a + 3*a
1 + 2*a^2 + 3*a