(x²+xy)/(x+y)² 分子提取公因式x=x(x+y)/(x+y)² 分子分母同时除以（x+y）=x/(x+y)x²-y²/（x²-y²）好像题目不对2xy/(x+y)²与x/x²-y² 公因式为(x+y)² (x-y)2x...