用平方差公式
(3x*(x-1)/(x^2-1)) - (x*(x+1)/(x^2-1)) + (x-2)/(x^2-1)
=(2x^2-3x-2)/(x^2-1)
=2+6√3
如果你题目那里是3x/(x+1) - x/(x-1) + (x-2)/(x^2-1)