=[3x(x+1)-x(x-1)/(x-1)(x+1)]x*x-1
=[2x*x+4x/(x-1)(x+1)]x*x-1
=[2x(x+1)+2x/(x-1)(x+1)]x*x-1
=(4x/x-1)(x+1)(x-1)
=4x(x+1)
=4x平方+4x
把X=根号2-2代入
=4*2-4根号2+4+4根号2-8
=0