Question

麻烦高手这两个式子怎么通分啊?公分母是x的立方+1..麻烦写的详细点

Answer 1

立方和

x³+1=(x+1)(x²-x+1)

所以原式=lim[(1-x+x²-3)/(1+x)(1-x+x²)]

=lim[(x-2)(x+1)/(1+x)(1-x+x²)]

=lim[(x-2)/(1-x+x²)]

=-1