已知1 x-1 y=5,求分式3x 5xy-3y 2x-3xy-2y的值

1/x+1/y=3∴x+y=3xy3x-2xy+3y/x+xy+y=[3(x+y)-2xy]/[(x+y)+xy]=(9xy-2xy)/(3xy+xy)=7/4

代入方法：分母：3x-3xy+3y=3(x+y)-3xy=3•(3xy)-3xy=9xy-3xy=6xy分子：x+xy+y=x+y+xy=3xy+xy=4xy所以原式=6xy/4xy=3/

已知1/x-1/y=3,应该是1/x+1/y=3,[按原式得不出结果!]如此,则3xy＝x+y（3x-xy+3y）/（x+xy+y）＝2

已知1/x-1/y=5,求分式的值分子分母同除以xy得：3x+5xy-3y/x-3xy-y=【3(1/y-1/x)+5】/【(1/y-1/x)-3】=(-15+5)/(-5-3)=10/8=5/4已知

1）由1/x-1/y=5,得(y-x)/xy=5,所以y-x=5xy,即x-y=-5xy(3x+5xy-3y)/(x-3xy-y)=[3(x-y)+5xy]/[(x-y)-3xy]=(-15xy+5x

因为x/y+z+y/z+x+z/x+y=1所以x/y+z=1-y/z+x-z/x+y,两边同乘以x得x^2/y+z=x-xy/z+x-xz/x+y同理y^2/x+z=y-xy/z+y-yz/x+y,z

首先化简通分1/x+1/y=5得：（x+y)/xy=5即有x+y=5xy将要求的分式化简：3x+xy+3y/x-2xy+y=3x+3y+xy/x+y-2xy（根据加法交换律）=3（x+y)+xy/(x

1.1/x-1/y=(y-x)/xy=5则y-x=5xy则有:3x-3y=-15xyx-y-3xy=-8xy原式=-10xy/(-8xy)=10/8=5/42.x+1/x=3则:(x+1/x)^2=3

1/x-1/y=5(y-x)/xy=5(x-y)/xy=-5(3x+5xy-3y)/(x-3xy-y)=[3(x-y)+5xy]/[(x-y)-3xy]=[3(x-y)/xy+5]/[(x-y)/xy

1/x-1/y=5(y-x)/xy=5y-x=5xyx-y=-5xy3x+5xy-3y/x-3xy-y=3(x-y)+5xy/(x-y)-3xy=3*(-5xy)+5xy/-5xy-3xy=-10xy

1/x-1/y=y-x/xy=5y-x=5xy3x-3y=-15xyx-y-3xy=-8xy原式=10xy/8xy=10/8=5/4

由1/x-1/y=3两边同乘以xy得y-x=3xy即x-y=-3xy所以(3x+3xy-3y)/(x-2xy-y)＝3(x-y+xy)/(x-y-2xy)=3(-3xy+xy)/(-3xy-2xy)=

因为:1/x-1/y=3(y-x)/xy=3x-y=-3xy（1）又因为：(2x+3xy-2y)/(x-2xy-y)=[2（x-y）+3xy]/[(x-y)-2xy]代入（1）得：（-6xy+3xy）

1/x-1/y=3（y-x）/xy＝3y-x＝3xy（4x-5xy－4y）/（3x-2xy-3y）＝（4（x－y）-5xy）/（3（x－y）－2xy）＝(4*-3xy-5xy)/(3*-3xy－2xy

将1/x-1/y=5通分,得y-x/xy=5,两边同时乘以xy,得y-x=5xy,带入-x+xy+y/2x+7xy-2y,得5xy+xy/-2*5xy+7xy,合并同类项,得6xy/-3xy=-2即,

由1/x-1/y=2001得：y-x/xy=2001所以：xy/y-x=1/2001xy/x-y=-1/2001x-xy-y/(x-y)=x-y-xy/(x-y)=1-xy/(x-y)原式=1+1/2

1/X-1/Y=5Y-X=5XY,(X-3XY-Y)/(3X+5XY-3Y)=［-(Y-X)-3XY］/［-3(Y-X)+5XY］=(-8XY)/(-10XY)=4/5.

解题方法：分子、分母同时除一个xy(y+xy-x)/(2x+7xy-2y)=[(y+xy-x)/xy]/[(2x+7xy-2y)/xy]=(1/x+1-1/y)/(2/y+7-2/x)=[(1/x-1

(y+xy-x)/(2x+7xy-2y)(分子、分母同除一个xy)=(1/x+1-1/y)/(2/y+7-2/x)=6/(-10+7)=-2

x+1/x=3,求分式x²+1/x²的值两边平方.∴x²+1/x²=9-2=72已知1/x-1/y=5,求分式xy/y-x的值解xy/（y-x）的倒数=1/x-