如果x分之1加y分之1=2求2x-3xy 2y-搜答案-搜搜考试网

3分之y-6分之(x+1)=3①①×6得：2y-x=19（3）②×6去括号得：6x+7y=0（4）把（3）x=2y-19代入（4）得19y=114y=6把y=6代入x=2y-19得x=-7

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

设1/X+1/Y=K（K＞0）通分得：（X+Y）/XY=K,X+Y=KXY又∵X+2Y=1,∴X=1-2Y,∴（1-2Y）+Y=K（1-2Y）×Y,整理得：2KY2-（1+K）Y+1=0,因为Y是正数

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=-1/21/x*1/y=1所以由韦达定理1/x,1/y是方程x²+x/2+1=0的根判别式小于0所以无解再问：x分之一加y分之一=1，x乘y分之1=负2分之求x、y,谢谢，感

2*1=1/(2X1)+1/(2+1)(1+a)=7/12,=>a=3,3*1=1/(3X1)+1/(3+1)(1+3)=19/48

(x²+2)/[x(x+1)(x+2)]=A/x+B/(x+1)+C/(x+2)(x²+2)/[x(x+1)(x+2)]=[A(x+1)(x+2)]+Bx(x+2)+Cx(x+1)

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,

分母不等于03x²-5x+2≠0(3x-2)(x-1)≠0所以x≠2/3且x≠1

1,4/(y²-1)+(y-3)/(1-y)+1=04-(y-3)(y+1)+(y²-1)=0y=-32,1/(x-3)-1/(x-4)=1/(x-6)-1/(x-7)1/(x-3

X/A+Y/B+D/C=1,A/X+B/Y+C/Z=0,求X/A+Y/B+Z/C的值?(BCX+ACY+ABD)/ABC=1====>BCX+ACY+ABD=ABC==>BCX+ACY=ABC-ABD

令2分之X=3分之y=4分之z=mX+Y+Z=2m+3m+4m=9mX+Y-Z=2m+3m-4m=m一比等于9

是椭圆x^2/a^2+y^2/b^2=1a^2=2b^2=3画出来是椭圆再问：厉害

原式=[(x+2y)/(x+y)]×[xy/(x+2y)]÷[(x+y)/xy]=[(x+2y)/(x+y)]×[xy/(x+2y)]×[xy/(x+y)]=x²y²(x+2y)/

3∵x/y=1/2∴y=2x故（x^2+2xy+y^2)/(x^2-xy+y^2)=(x+y)^2/(x^2-xy+y^2)=(x+2x)^2/(x^2-x·2x+4x^2)=9x^2/(3x^2)=

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{3分之y减6分之x加1=3,2(x-2分之y)=3（x加18分之yy/3-(x+1/6)=32y-6x=19(1)2(x-y/2)=3(x+y/18)2x-y=3x+y/612x-6y=18x+y6

1/x-2/y=225/x+7/y=22一式*5-二式得-17/y=88y=-17/88x=17/198

利用柯西不等式(2/x+4/y)(x+y)≥(√2+2)²当且仅当x=2+4√2且y=4+2√2时取等∵2/x+4/y=1∴(x+y)≥(√2+2)²=6+4√2即(x+y)≥6+