原式={[(x+1)²-(x-1)²]/(x+1)(x-1)}÷[x/(x+1)(x-1)]-1
=[(x+1+x-1)(x+1-x+1)/(x+1)(x-1)]×(x+1)(x-1)/x]-1
=2x/(x+1)(x-1)×(x+1)(x-1)/x-1
=2-1
=1