Question

先化简再求值：

x²-1/x²-2x+1÷x+1/x-1•1-x/1+x，其中x＝1/2

Answer 1

原式=(x+1)(x-1)/(x-1)²*(x-1)/(x+1)*[-(x-1)/(x+1)]
=(x+1)/(x-1)*(x-1)/(x+1)*[-(x-1)/(x+1)]
=-(x-1)/(x+1)

Answer 2

解原式=(x-1)(x+1)/(x-1)²÷(x+1)/(x-1)×(1-x)/(1+x)=(x+1)/(x-1)×(x-1)/(x+1)×(1-x)/(1+x)=(1-x)/(1+x)=(1-1/2)/(1+1/2)=1/2×2/3=1/3