∵1/x-1/y=4∴(y-x)/xy=4∴y-x=4xy∴x-y=-4xy(2x+xy-2y)/(x-2xy-y)=[2(x-y)+xy]/[(x-y)-2xy]=(-8xy+xy)/(-4xy-2xy)=(-7xy)/(-6xy)=7/6很高兴为您解答,【the 1900】团队为您答题.请点击下面的【选为满意回答】按钮....