先化简再求值：(x减1分之3x减x加1分之x)乘以x分之x的平方减1,其中x=2

原式=[3x/(x-1)-x/(x+1)]×[(x²-1)/x]
={3x(x+1)/[(x-1)(x+1)]-x(x-1)/[(x-1)(x+1)]}×[(x-1)(x+1)/x]
=[3x(x+1)-x(x-1)]/x
=(3x²+3x-x²+x)/x
=(2x²+4x)/x
=2x+4
=2×2+4
=8