x²-2xy+y²/x²-xy÷(xy的-1次方-x的-1次方y)=（x-y）²/x(x-y)÷（x/y-y/x）=(x-y)/x÷(x²-y²)/xy=(x-y)÷（x+y）（x-y）/y=y/(x+y)=√3/(3-√3+√3)=√3/3