x^3-3x^2+4=x^3+1-3x^2+3=(x^+1)(x^2-x+1)-3(x-1)(x+1)=(x+1)(x^2-x+1-3x+3) =(x+1)(x^2-4x+4)=(x+1)(x-2)^2=0所以x+1=0x-2=0x=-1 或x=2