解：由x^3+3x-4=0得x^3-1+3(x-1)=0 (x-1)(x^2+x+1)+3(x-1)=0(x-1)(x^2+x+4)=0 如有疑问继续追问，谢谢采纳！
x^3+3x-4 =x^3-1+3(x-1)= (x-1)(x^2+x+1)+3(x-1)= (x-1)(x^2+x+4)
