[1/(1+x)+1/(x-1)]÷[x/(1-x²)-x)]的值=[1/(1+x)-1/(1-x)]÷[(x-x(1-x²))/(1-x²)]=[(1-x-1-x)/(1-x²)]÷[(x-x-x³)/(1-x²)]=[(-2x)/(1-x²)]×[(1-x²)/(-x³)]=2/x²已知x²/(x²-2)=1/(1+√3-√5)1/(1-2/x²)=1/(1+√3-√5),(1-2/x²)=(1+√3-√5),2/x²=√5-√3则原式=2/x²=√5-√3