先化简再求值：x的平方-1/x的平方-2x+1除以x+2/x-1减去1/x+2,其中x=2
问题描述：
先化简再求值：x的平方-1/x的平方-2x+1除以x+2/x-1减去1/x+2,其中x=2
答
x的平方-1/x的平方-2x+1除以x+2/x-1减去1/x+2
=(x-1)(x+1)/(x-1)² ÷ (x+2)/(x-1) -1/(x+2)
=(x+1)/(x-1)* (x-1)/(x+2) -1/(x+2)
=(x+1-1)/(x+2)
=x/(x+2)
=2/(2+2)
=1/2