（x-1分之3x-x+1分之x）*x分之x的平方-1
=[3x(x+1)-x(x-1)]/x
=3(x+1)-(x-1)
=3x+3-x+1
=2x+4
=2√2-4+4
=2√2确定么确定啊，楼下也是相同的答案呀恩，谢谢