一道初二数学题!!!

已知1/x+1/y=5,求2x-3xy+2y/x+2xy+y的值
2025-05-24 06:22:43
推荐回答(5个)
回答1:

2x-3xy+2y/x+2xy+y
=[(2x-3xy+2y)/xy]/[(x+2xy+y)/xy]
(利用分式的基本性质,分子、分母同时除以xy).
=〔(2/y)-3+(2/x)]/[(1/y)+2+(1/x)]
=(10-3)/(5+2)
=1

回答2:

2x-3xy+2y/x+2xy+y
=[(2x-3xy+2y)/xy]/[(x+2xy+y)/xy]
(利用分式的基本性质,分子、分母同时除以xy).
=〔(2/y)-3+(2/x)]/[(1/y)+2+(1/x)]
=(10-3)/(5+2)
=1

回答3:

∵1/x+1/y=5
∴xy≠0
利用分式的基本性质,分子、分母同时除以xy≠0
2x-3xy+2y/x+2xy+y
=[(2x-3xy+2y)/xy]/[(x+2xy+y)/xy]
=〔(2/y)-3+(2/x)]/[(1/y)+2+(1/x)]
=(10-3)/(5+2)
=1

回答4:

原式=2-7xy/(x+2xy+y)
7xy/(x+2xy+y)的倒数化简为 1/7y+2/7+1/7x
1/7y+1/7x=5/7,所以7xy/(x+2xy+y)=1,原式=1
:)

回答5:

随便取几个值试试;一般这种题答案都是1