(1)x^3-1=0,设x1、x2、x3是1的三个立方根,(x-1)(x^2+x+1)=0,x1=1,x2=-1/2+√3i/2,x3=-1/2-√3i/2,（2）(1/8)^(1/3),x1=1/2,x2=(1/2)(-1/2+√3i/2)=-1/4+√3i/4,x3=(1/2)(-1/2-√3i/2))=-1/4-√3i/4,(-27)^(1/3),x1=-...