已知1⼀x-1⼀y=4,求分式2x+3xy-2y⼀x-2xy-y的值

2024-12-30 17:07:47
推荐回答(2个)
回答1:

解:把已知1/x-1/y=4通分得:(y-x)/xy=4,有:y-x=4xy,即
(2x+3xy-2y)/(x-2xy-y)=[2(x-y)+3xy]/(x-y-2xy)=(3xy-8xy)/(-2xy-4xy)=[-5xy]/(-6xy)=5/6

回答2:

解:(2x+3xy-2y)/(x-2xy-y)=[2(x-y)+3xy]/(x-y-2xy)
分子、分母同除以xy得:(因为:xy都不等于0)
原式=[2(1/x-1/y)+3]/(1/x-1/y-2)=(2*4+3)/(4-2)=11/2