(x的平方-2x+1)/(x的平方-1)除以(2x-2)/(x+1)
=(x-1)^2/(x-1)(x+1)÷2(x-1)/(x+1)
=(x-1)/(x+1)÷2(x-1)/(x+1)
=1/2
可见不论x取何值,代数式的值都等于1/2.