lim[3/ 1-x^3+1/x-1]

lim[3/(1-x³) + 1/(x-1)]=lim [ - 3/(x³-1) + (x²+x+1)/(x-1)(x²+x+1) ]=lim (x²+x -2) / [(x-1)(x²+x+1)]=lim (x-1)(x+2) / [(x-1)(x²+x+1)]=lim (x+2)/(x²+x+1)= 1你怎么知道要分子分母同乘以x^2+x+1的啊？谢谢哦这里需要通分。因为x3-1=(x-1)(x2+x+1)所以1/(x-1)需要分子分母同乘以x2+x+1哦，知道了，谢谢不客气。如果没问题了请采纳吧o(∩_∩)o