(3x-3/x²-1)÷(3x/x+1)-1/x-1
=3（x-1）/[(x+1)(x-1)] ÷[3x/(x+1)] -1/(x-1)
=1/x-1/(x-1)
=(x-1-x)/x(x-1)
=-1/x(x-1)
=1/(x-x²)
如果本题有什么不明白可以追问,