【1/（x-y）-1/（x+y）】÷(xy²)/（x²-y²）=[1/(x-y)-1/(x+y)]×(x+y)(x-y)/(xy²)=(x+y)/(xy²-(x-y)/(Xy²)=(x+y-x+y)/(xy²)=2/(xy)当x=1-√2,y=1+√2时原式=2/[(1-√2)(1+√2)]=...