2xy/(x+y) ²= 2xy/((x+y)(x+y))x/(x²-y²)=x/((x+y)(x-y))所以公分母为 (x+y)(x+y)(x-y)所以通分结果为：2xy/(x+y) ² = 2xy(x-y)/((x+y) ²(x-y))x/(x²-y²) = x(x+y)/((x+y) ²...