先化简在求值
问题描述：
先化简在求值
(x/x-1-1/x²-x)÷(x＋1),其中x=1/2
答
[x/(x-1)-1/(x²-x)]÷(x＋1)
=[x²/x(x-1)-1/x(x-1)]÷(x＋1)
=(x²-1)/x(x-1)÷(x＋1)
=(x+1)(x-1)/x(x-1)÷(x＋1)
=(x+1)/x÷(x＋1)
=1/x
=1/(1/2)
=2