(x-x+1/x)÷(1+x²-1/1)=[(x+1)/(x²+x-x)]÷[(x²-1)/(x²-1+1)]=[(x+1)/(x²)]÷[(x²-1)/(x²)]=[(x+1)/(x²)]*[(x²)/(x-1)(x+1)]=x-1当x=2时上式=1