1/(x-1)-3/(x的3次方-1)怎样通分?
问题描述：
1/(x-1)-3/(x的3次方-1)怎样通分?
答
=1/(x-1)-3/(x-1)(x^2+x+1)
=(x^2+x+1-3)/(x-1)(x^2+x+1)
=(x^2+x-2)/(x-1)(x^2+x+1)
=(x-1)(x+2)/(x-1)(x^2+x+1)
=(x+2)/(x^2+x+1)