先化简,(x²-1)÷x÷[1-(2x-1)÷(x-1)],再选取一个适当的x的值代入计算.
问题描述:
先化简,(x²-1)÷x÷[1-(2x-1)÷(x-1)],再选取一个适当的x的值代入计算.
答
(x²-1)÷x÷[1-(2x-1)÷(x-1)]
(2x-1)÷(x-1)=(2x-1)/(x-1)=[2(x-1)+1]/(x-1)=2+1/(x-1) ……①
[1-(2x-1)÷(x-1)]=[(x-1)-(2x-1)]/(x-1)=-x/(x-1)=x/(1-x)……②
x÷[1-(2x-1)÷(x-1)]=x/x/(1-x)=1-x……③
(x²-1)÷x÷[1-(2x-1)÷(x-1)]=(x²-1)/(1-x)=(x+1)(x-1)/(1-x)=-x-1……④
把x=2代入 -x-1 = -3
把x=2代入原式:(4-1)/2/(1-3/1)=-3
说明化简正确
PS.可能看着有点乱 就是从右往左化简
(x²-1)÷x÷[1-(2x-1)÷(x-1)]
先化简(2x-1)÷(x-1)也就是①
然后1-(2x-1)÷(x-1)也就是②
接着是x÷[1-(2x-1)÷(x-1)] 也就是③
最后是全部的(x²-1)÷x÷[1-(2x-1)÷(x-1)] 也就是④