2
{（-1+根号3i）/2}的3次方=1
{（-1-根号3i）/2}的3次方=1
{（-1+根号3i）/2}的3次方=（cos2π/3+isin2π/3）^3=（cos2π+isin2π）=1
{（-1-根号3i）/2}的3次方=（cos4π/3+isin4π/3）^3=（cos4π+isin4π）=1