2 z - z + 1
z^2 - z + 1
/ ___\ / ___\ | 1 I*\/ 3 | | 1 I*\/ 3 | |x + - - + -------|*|x + - - - -------| \ 2 2 / \ 2 2 /
(x - 1/2 + i*sqrt(3)/2)*(x - 1/2 - i*sqrt(3)/2)
2 1 + z - z
1 + z^2 - z
1.0 + z^2 - z
1 + z*(-1 + z)