xy分之1=1,x和y.

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

1/x+1/y=2则(2x+3xy+2y)/(x-xy+y)分子分母同除以xy=(2/x+2/y+3)/(1/x+1/y-1)=(4+3)/(2-1)=7

1/X+1/Y=3即x+y=3xy(2x+3xy+2y)/(x-2xy+y)=(2*3xy+3xy)/(3xy-2xy)=9xy/xy=9答案为9

解1/x+1/y=5即(y+x)/xy=5∴y+x=5xy∴(2x+3xy+2y)/(x-2xy+y)=[2(x+y)+3xy]/[(x+y)-2xy]=[2×5xy+3xy]/(5xy-2xy)=(

由1/x-1/y=3得(y-x)/xy=3题中的式子分子分母同时除以xy得(2/y+3-2/x)/(1/y-2-1/x),通分得【2(x-y)/xy+3】/【(x-y)/xy-2】代入得3/5

1/x-1/y=2(y-x)/xy=2y-x=2xy所以x-y=-2xy原式=[2(x-y)+7xy]分之[(y-x)+xy]=[2(-2xy)+7xy]分之[(2xy)+xy]=3xy]分之3xy=

1/x-1/y=2001则(x-xy-y)/(x-y)=2002/2001

3xy-[2xy-2(xy-2分之3xy)+xy]+3xy=6xy-[2xy-2xy+3xy+xy)=6xy-4xy=2xy=2×3×3分之1=2

1/x+1/y=-2则(x-xy+y)/(x+xy+y)分子分母同除以xy=(1/x+1/y-1)/(1/x+1/y+1)=(-2-1)/(-2+1)=3

(x分之1)+(y分之1)=5（x+y)/xy=5x+y=5xy代入（x+2xy+y)分之(2x-3xy+2y)=7xy分之7xy=1

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

原式(-xy/3)²*[xy(2x-y)-2x(xy-y²)]=(x²y²/9)(2x²y-xy²-2x²y+2xy²)

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

1、(xy分之x²-y²)×(x-y分之x)-(y分之x)；=(x+y)(x-y)/xy×x/(x-y)-x/y=(x+y)/y-x/y=(x+y-x)/y=12、6xy²

设1/x-1/y=t(5x+xy-5y)/(x-xy-y)=(1-5(1/x-1/y))/(-1-(1/x-1/y))=(5t-1)/(t+1)至于是1/x-1/y=3还是1/y-1/x=3都差不多

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

x分之1-y分之1=-3所以(y-x)/xy=-3y-x=-3xy从而3x-2xy-3y分之x+3xy-y=（3xy+3xy）/(3×3xy-2xy)=6/7

(X-Y)^2=x^2+y^2-2xy=5/42xy=x^2+y^2-5/42xy+x+y+1=0可以化为x^2+y^2+x+y+1-5/4=0(x+1/2)^2+(y+1/2)^2-3/4=0又因为

[(xy-2)(-xy-2)-4(xy-1)^2]除以(-xy)=[-x²y²+4-4(x²y²-2xy+1)]÷(-xy)=(-x²y²+

分子上应写：（x-1）²或者x²-2x+1再问：怎么书面表达呢？能否详细一些，谢谢再答：希望你及时采纳！！！！！