已知1/x+1/y=3,求3x-2xy+3y/x+5xy+y的值

来源：学生作业学帮网编辑：学帮网时间：2024/06/16 22:57:40

1/x+1/y=3
(x+y)/xy=3
x+y=3xy
(3x-2xy+3y)/(x+5xy+y)
=[3(x+y)-2xy]/[(x+y)+5xy]
=(3*3xy-2xy)/(3xy+5xy)
=7xy/8xy
=7/8