已知x 分之一减去y分之一等于3,求分式x-2xy-y分之2x-3xy-2y的值-搜答案-灵鹊做题网

1/x-1/y=3等号左边通分,得(y-x)/(xy)=3故x-y=-3xy代入分式[2x+3xy-2y]/[x-2xy-y]=[2(x-y)+3xy]/[(x-y)-2xy]=(-6xy+3xy)/

答：1/x+1/y=3(x-2xy+y)/(2x+xy+2y)分子分母同除以xy得：=(1/y-2+1/x)/(2/y+1+2/x)=(3-2)/(3*2+1)=1/7

1／X－1／Y＝3（Y－X）／XY＝3Y－X＝3XY〔－2（Y－X）＋3XY〕／〔－（Y－X）－2XY〕＝（－6XY＋3XY）／（－3XY－2XY）＝－3XY／－5XY＝3／5

答案有很多,其中一个是16分之257再问：过程步骤

14

x分之1-y分之1=4(xy)分之(y-x)=4y-x=4xyx-y=-4xy(x-2xy-y)分之(2x+xy-2y)=[(x-y)-2xy]分之[2(x-y)+xy]=(-4xy-2xy)分之(-

1/X-1/Y=4Y-X=4XY(2X+XY-2Y)/(X-2XY-Y)=[2(X-Y)+XY]/[(X-Y)-2XY]=7/6

1/x-1/y=5（y-x）/xy=5y-x=5xyx-y=-5xy（3x+5xy-3y）/（x-3xy-y）=【3×（-5xy）+5xy】/（-5xy-3xy）=-10xy/-8xy=5/4

5.4x次幂等于3所以x=log(5.43)5.4代表底数3代表指数y=log(0.63)0.6代表底数3代表指数所以x分之一减去y分之一=[分之一减去[log(0.63)]分之一由换底公式得上式=[

X平方分之一加Y平方分之一=（X分之一减去Y分之一）²+2/（xy)=5²-2=23

1/x-1/y=2同时乘以xyy-x=2xyx-y=-2xy[3(x-y)+5xy]/[(x-y)-xy]=(-6xy+5xy)/(-2xy-xy)=(-xy)/(-3xy)=1/3

1/X-1/Y＝5（Y-X）/XY＝5Y-X＝5XY（3x+7xy-3y）/（2x-3xy-2y）＝[3（X-Y）+7XY]/[2（X-Y）-3XY]＝[-3（Y-X）+7XY]/[-2（Y-X）-3

X分之一减去Y分之一等于1(y-x)/(xy)=1y-x=xyx-y=-xyx-2xy-y分之2x+3xy-2y=[2(x-y)+3xy]/[(x-y)-2xy]=(-2xy+3xy)/(-xy-2x

①∵（x^4＋x²＋1）/x²＝x²＋1＋1/x²∴原式＝1/（x²＋1＋1/x²）②∵1/x－1/y＝（y－x）/xy＝3∴x－xy－y＝

答案是4.先把已知条件通分,化简,得到X-Y=-3XY,在把它带入所求式子,为：-5XY分之-20XY.

得xy分之y-x=3得y-x=3xy带入得-9xy-5xy分之-3xy-2xy得14分之5..求采纳.谢谢

[2x+14xy-2y]/[3x-2xy-3y]=(2/y+14-2/x)/(3/y-2-3/x)分子分母同时除以xy=[-2(1/x-1/y)+14]/[-3(1/x-1/y)-2]=(-6+14)

1/x-1/y=5y/(xy)-x/(xy)=5y-x=5xyx-y=-5xy(2x-11xy-2y)/(x-2xy-y)=[2(x-y)-11xy]/(x-y-2xy)=[2(-5xy)-11xy]

x+y=3xy(1-3x)(1-3y)=1-3(x+y)+9xy=1所以1/[(1-3x)(1-3y）]=1

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)=