/ ___\ / ___\ / ___\ / ___\ | 1 I*\/ 7 | | 1 I*\/ 7 | | 1 I*\/ 7 | | 1 I*\/ 7 | |x + - + -------|*|x + - - -------|*|x + - - + -------|*|x + - - - -------| \ 2 2 / \ 2 2 / \ 2 2 / \ 2 2 /
(((x + 1/2 + i*sqrt(7)/2)*(x + 1/2 - i*sqrt(7)/2))*(x - 1/2 + i*sqrt(7)/2))*(x - 1/2 - i*sqrt(7)/2)