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