若1/x-1/y=4,则x+5xy-y/x-3xy-y的值为_____

问题描述:

若1/x-1/y=4,则x+5xy-y/x-3xy-y的值为_____

1/x-1/y=4
x=y-4xy
代入x+5xy-y/x-3xy-y
=xy/-7xy
=-1/7