先化简,再求值.x^3/(x-1)-1/(1-x)-x^2-x-1,其中x=1/2.
问题描述：
先化简,再求值.x^3/(x-1)-1/(1-x)-x^2-x-1,其中x=1/2.
答
=(x³+1)/(x-1)-(x²+x+1)(x-1)/(x-1)
=(x³+1)/(x-1)-(x³-1)/(x-1)
=(x³+1-x³+1)/(x-1)
=2/(x-1)
=-4