∵1,α1,α2,α3,α4 are the roots of z5−1=0 ⇒(z−1)(z−α1)(z−α2)(z−α3)(x−α4)=z5−1 ⇒(ω−1)(ω−α1)(ω−α2)(ω−d3)(ω−α4)=ω5−1 (ω−1)(ω−α1)(ω−α2)(ω−α3)(ω−α4)+ω =(ω5−1)+ω=ω2−1+ω =−1−1=−2