已知x分之1减y分之1等于2的变式有-搜答案-大师作文网

1/x-1/y=3得y-x=3xy∴xy=(y-x)/3则x-xy-y=x-y-(y-x)/3=4(y-x)/35x+xy-5y=5(x-y)+(y-x)/3=14(x-y)/3∴(5x+xy-5y)

分子分母同除以xy,分子变为2（1/x+1/y)+3=2x3+3=9分母变为（1/x+1/y)+2=3+2=5答案是9/5

x=4m-1/2x+1/2=4m(x+1/2)/4=my=m+1/4y-1/4=m(x+1/2)/4=y-1/4x+1/2=4y-1x+3/2=4y

再问：2/5再答：？

x/2=y/3=z/4=tx=2ty=3tz=4tx+y-z=1/122t+3t-4t=t=1/12x=1/6y=1/4z=1/3xyz=1/6*1/4/*1/3=1/72

直接设X=1,Y=0.5.带入后式得出10

/>1/x-1/y=3(y-x)/(xy)=3y-x=3xyx-y=-3xy(2x-14xy-2y)/(x-2xy-y)=[2(x-y)-14xy]/[(x-y)-2xy]=[2×(-3xy)-14x

1/x-1/y=4(y-x)/xy=4x-y=-4xy(3X+5xy-3y)/(x-3xy-y)=[3(x-y)+5xy]/[(x-y)-3xy]=(-12xy+5xy)/(-4xy-3xy)=1

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

解析：

此题简单做法你直接可以设X=1,Y=0.5,使其满足前面的条件即可,带入后面分式,后面的式子中文表述不清,

（X+Y）/2-(X-Y)/3=1?如果是这样的话等式两边同时乘以公倍数6得到的答案是Y=(6-X)/5

1/x-1/y=(y-x)/xy=3y-x=3xy(2x-5xy-2y)/(3x-10xy-3y)=-8xy/-19xy=8/19自己算一下直接看着算的反正就是整体代入思想

∵y=1/3x-1∴1/3x²-2xy+3y²-2=1/3x²-2x（1/3x-1）+3（1/3x-1）²-2=1/3x²-2/3x²+2x

因为1/x+1/y=-3所以(x+y)/xy=-3即x+y=-3xy所以(x-6xy+y)/(3x+2xy+3y)=(-3xy-6xy)/[3(x+y)+2xy)]=-9xy/(-9xy+2xy)=9

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

(1/3)^(-x)=2.即：3^x=2.所以：(3^x)^4=((3^2)^x)^2=9^2x=2^4=16.1/3^(-y)=5.即：3^y=5.所以：(3^y)^2=(3^2)^y=9^y=25

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

1/x-1/y=3(y-x)/(xy)=3y-x=3xyx-y=-3xy(2x+3xy-2y)/(x-2xy-y)=[2(x-y)+3xy]/[(x-y)-2xy]=(-6xy+3xy)/(-3xy-