2 3 a + a - a
a + a^2 - a^3
/ ___\ / ___\ | 1 \/ 5 | | 1 \/ 5 | a*|a + - - + -----|*|a + - - - -----| \ 2 2 / \ 2 2 /
(a*(a - 1/2 + sqrt(5)/2))*(a - 1/2 - sqrt(5)/2)
/ 2\ a*\1 + a - a /
a*(1 + a - a^2)
/ 2 \ -a*\-1 + a - a/
-a*(-1 + a^2 - a)