若3x^2+xy-2y^2=0,求（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)的值

若3x^2+xy-2y^2=0,求（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)的值
若3x^2+xy-2y^2=0,求（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)的值

若3x^2+xy-2y^2=0,求（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)的值
3x^2+xy-2y^2=0
(3x-2y)(x+y)=0
因为4xy/（y^2-x^2）有意义,所以,x+y≠0
所以,3x-2y=0
y=3x/2
（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)
=[(x+y)^2-4xy]/(x-y)(x+y)除以(x+3y)(x-y)/(x-3y)(x+3y)
=(x-y)^2/(x-y)(x+y)除以(x-y)/(x-3y)
=(x-y)/(x+y)除以(x-y)/(x-3y)
=(x-3y)/(x+y)
=(x-3*3x/2)/(x+3x/2)
=(-7x/2)/(5x/2)
=-7/5