Z^2 = 1 , Z=±1 Z^3 = 1 , Z=ω,ω^2 ⇔ Z^3 - 1 = 0 ⇔(Z-1)(Z^2 + Z+1) = 0 Z=1, Z= (-1±√3i) / 2 Z^4 = 1 ,
円分方程式