当X Y分之X减Y等于二

1/X-1/Y=3分子分母同除以xy=(1/y-2-1/x)/(2/y+3-2/x)=(1*3-2)/(2*3+3)=1/9

(y-x)/xy=3求（2x+3xy-2y)/(x-2xy-y)?(y-x)/xy=3-->1/x-1/y=3-->y-x=3xy（2x+3xy-2y)/(x-2xy-y)=(x-y)/(-5xy)=

xy分之x加y等于2∴x+y=2xy3x减5xy加3y分之负x加3xy减y=[-(x+y)+3xy]/[3(x+y)-5xy]=(-2xy+3xy)/(6xy-5xy)=xy/(xy)=1

由　1/X-1/Y=5,两边同乘　XY,得出Y-X=5XY,那么　　分子　-X+XY+Y=6XY分母　2X+7XY-2Y=7XY-2(Y-X)=-3XY　　得此分式的值为－再问：还有一题x+x分之一=

3x^2y-xy^2=xy(3x-y)将x=-1/2y=1代入有-1/2*1*[3*(-1/2)-1]=-1/2*(-5/2)=5/4

x减1分之x平方减1,化简为x+1得2005+1=2006第二问不太清楚

x-3xy-Y分之3x+5xy-3y==(3x+5xy-3y)/(x-3xy-Y)=(5+3*(1/y-1/x))/(-3+(1/y-1/x)).分子分母同时除以xy=(5-21)/(-3-7).将x

解析：

x分之1减y分之1等于2（y-x）xy=2y-x=2xyy减xy减x分之3x加xy减3y=[3(x-y)+xy]/(y-x-xy)=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5

5xy/(2x-y)=2所以10xy/(2x-y)=4所以(2x-y)/(10xy)=1/415xy/(6x-3)=3×5xy/[3(2x-y)]=5xy/(2x-y)=2

x分之一减y分之一等于2分之1所以xy分之y-xy分之x=2分之1,xy分之（y-x）=2分之1,y-x=2分之xy,x-y=负2分之xy,所以x减y分之xy=（负2分之xy）分之xy=-xy分之（2

如果题目是:"x的平方减xy分之y加y的平方减xy分之x",那么就是你的那个答案.y/(x^2-xy)+x/(y^2-xy)=y/[x(x-y)]+x/[y(y-x)]=y^2/[xy(x-y)]-x

1/x-1/y=3y-x=3xy(x-2xy-y)/(2x+3xy-2y)=(-3xy-2xy)/(-6xy+3xy)=5/3

因为1/x-1/y=3所以方程左边先通分得y/xy-x/xy=3即（y-x）/xy=3所以得y-x=3xy（这一步很关键,一会要用整体代入法)要求的分数的分子：x+xy-y=xy-3xy=-2xy(因

1/x-1/y=5通分(y-x)/xy=5y-x=5xyx-y=-5xy原式=[3(x-y)+5xy]/[(x-y)-3xy]=(-15xy+5xy)/(-5xy-3xy)=-10xy/(-8xy)=

1/x-1/y=3y-x=3xyx-y=-3xy(5x-xy-5y)/(x-xy-y)=(-15xy-xy)/(-3xy-xy)=4

x分之1减y分之1等于31/x-1/y=3(y-x)/xy=3y-x=3xy所以x-xy-y分之5x-xy-5y=（-3xy-xy）分之(-15xy-xy)=-4分之（-16）=4

由已知条件可得：x-y=-4xy,（也就是在等式两边乘xy后整理,即可）,代入所求的式子里分母为-4xy+7xy,即3xy；分子为-4xy-2xy,即-6xy,化简得-2

已知xy/(x+y)=2,求:(3x-5xy+3y)/(-x+3xy-y)xy/(x+y)=2得：xy=2(x+y)(3x-5xy+3y)/(-x+3xy-y)=(3x-9xy+3y+4xy)/(-x

（2x-y）分之5xy与10xy分之（2x-y）的乘积为0.5,前者等于2,后者等于0.25代数式6x-3?没写完?