先化简,再求值.x^3/(x-1)-1/(1-x)-x^2-x-1,其中x=1/2._数学解答

先化简,再求值.x^3/(x-1)-1/(1-x)-x^2-x-1,其中x=1/2.

人气：221 ℃　时间：2020-02-06 00:50:28

解答

=(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