分式的约分与通分问题约分 (x²+xy)/(x+y)² x²-y²/（x&sup

(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)2xy/(x+y)²=2xy(x-y)/{(x+y)²(x-y)} x/(x²-y²)=x(x+y)/{(x+y)²(x-y)} 说明x²-y² =(x+y)(x-y) x-y/2x+2y与xy/(x+y)² 公因式为2(x+y)² x-y/2x+2y=(x-y)/{2(x+y)}=(x+y)(x-y) /{2(x+y))(x+y)}=x+y)(x-y) /{2(x+y)²}xy/(x+y)²=2xy/{2(x+y)²}