化简求值：[3x/(x-1)-2x/(x+1)*(x2-1)/x 其中x=根号5 -5
问题描述：
化简求值：[3x/(x-1)-2x/(x+1)*(x2-1)/x 其中x=根号5 -5
答
原式=[3x/(x-1)-2x/(x+1)]*(x+1)(x-1)/x
=3x/(x-1)*(x+1)(x-1)/x-2x/(x+1)*(x+1)(x-1)/x
=3(x+1)-2(x-1)
=3x+3-2x+2
=x+5
=√5-5+5
=√5