2xy/x平方-y平方-x/x+y+y/y-x
=[2xy-x(x-y)-y(x+y)]/(x+y)(x-y)
=（2xy-x²+xy-xy-y²）/(x+y)(x-y)
=(2xy-x²-y²)/(x+y)(x-y)
=-(x-y)²/(x+y)(x-y)
=(y-x)/(x+y)
=（2-3）/(3+2)
=-1/5
如追加其它问题,