初二数学难题 分式方程组 高手进

①式左边通分得-2x/(x+y)(y-x)=8/15 ...③
②式左边通分得到5x/y(x+y)=4...④
③/④并化简得到 y/(y-x)=-1/3 可算出x=4y
x=4y代入①或②
结果:x=4,y=1

①式左边通分得-2x/(x+y)(y-x)=8/15 ...③ ②式左边通分得到5x/y(x+y)=4...④ ③/④并化简得到 y/(y-x)=-1/3 可算出x=4y x=4y代入①或② 结果:x=4,y=1

{1/(x+y)-1/(y-x)=8/15 ①
{5/(x+y)-5/y=-4 ②
解：由①得:1/(x+y)+1/（x-y）=8/15
2x/(x+y)(x-y)=8/15
2x=8/15x2+8/15y2③
由②得:5y/y(x+y)-5x+5y/y(x+y)=-4
-5x/y(x+y)=-4
-5x=-4xy+ -4y2④
③+④得：y=3/2
将其带入④得：x=-9
{x=-9
{y=-3/2