【（x²-2x+1）分之x+（1-x）分之1】÷（x²-1）分之2
=[x/(x-1)²-1/(x-1)×(x+1)(x-1)/2
=(x-x+1)/(x-1)×(x+1)(x-1)/2
=(x+1)/2
当x=-2时
原式=（-2+1)/2=-1/2