已知x^2-5XY+4y^2=0求分式x-y/x+y的值⊙﹏⊙b汗.

已知x^2-5XY+4y^2=0求分式x-y/x+y的值⊙﹏⊙b汗.
已知x^2-5XY+4y^2=0求分式x-y/x+y的值⊙﹏⊙b汗.

已知x^2-5XY+4y^2=0求分式x-y/x+y的值⊙﹏⊙b汗.
x²－5xy＋4y²=0
(x－4y)(x－y)=0
即：x－4y=0得：x=4y或者：x－y=0得：x=y
则：(x－y)(x＋y)
1、若x=y,则这个值是0
2、若x=4y,则=(4y－y)/(4y＋y)=3/5

(x-2y)^2=0 => x=2y => (2x-y)/(2x+y) =(4y-y)/(4y+y) =3/5