x y=162 ⅹ=yx0.2过程

x(x的平方+xy+y的平方)-y(x的平方+xy+y的平方)+3xy(y-x)=(x-y)(x的平方+xy+y的平方)+3xy(y-x)=(x-y)(x的平方+xy+y的平方-3xy)=(x-y)(

x=3/2(6+9/2Y+2Y)/(-6+12Y-2Y)故这样的话这题是解不出来滴故原题我预测应该是1/X+2/Y=2有：Y+2X=2XY原式可以化为：（4XY+3XY)/(-4XY+8XY)=7/4

提示：构造x+y,xy.(2x+3xy+2y)/(x²y+xy²)=[2(x+y)+3xy]/[(xy)(x+y)]=(2×12+3×9)/(9×12)=17/36

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

|xy|-|2x|+|y|=4==>|x||y|-2|x|+|y|=4==>|x||y|+|y|-2|x|-2=2==>(|y|-2)(|x|+1)=2|x|+1为正整数|y|-2也为正整数2分解质因

1.2(Xy+Xy)-3(Xy-xy)-4Xy=2*2xy-0-4xy=4xy-4xy=02.1/2ab-5aC-(3acb)+(3aC-4aC)=1/2ab-5ac-3acb-ac=1/2ab-6a

这个是非齐次的一阶线性微分方程首先求它对应的齐次线性方程的y'-2xy=0,dy/dx=2xy,dy/y=2xdx,∫dy/y=∫2xdx,lny+C1=x²+C2,y=Ce^(x²

x+y=7-xyx^2+y^2=10即(x+y)^2=(7-xy)^2=x^2+y^2+2xy=10+2xy即(7-xy)^2=10+2xy即x^2y^2+39-16xy=0解得xy=3代入x+xy+

x²+xy-2y²=2(x+2y)x²+(y-2)x-2y²-4y=0x²+(y-2)x-2y(y+2)=0(x+2y)(x-y-2)=0解得x=-2

2[xy+(-3x)]-3(2y-xy)=2xy-6x-6y+3xy=5xy-6(x+y)=3

x-y=(x-xy)+(xy-y)=40+(-20)=20x+y-2xy=(x-xy)-(xy-y)=60希望满意!

因为x2-xy=40xy-y2=-20所以x2-y2=x2-xy+xy-y2=203x2-5xy+2y2=3(x2-xy)-2(xy-y2)=160

2X-Y=1/3XY=24X^3y-3x^2y^2+xy^3=4X^3y-4x^2y^2+xy^3+x^2y^2=xy(4X^2-4xy+y^2)+x^2y^2=xy(2x-y)^2+x^2y^2=2

2x^2+xy=6…………①3x^2+2xy=9…………②①×2－②,得x^2=3,带入①得y=0原式=4x^2=4×3=12

3x^2-4xy+y^2=-3,(1)2x^2+3xy-2y^2=8,(2),(1)X3-(2)X2得：5x^2-18xy+7y^2=-3x3-8x2=-25

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

式子写的不够严密,我是按照：（1+2y^2/(x^2-y^2))/(1+2y/(x-y))做的.只要把y=3x代入式子中计算即可,没什么关键的步骤啊,都是纯计算.答案是5/8还有一题,刚才没看到同样,

你是说初一下册教科书中的二元一次单元章的那道题?我当时也不相信...大胆尝试,最后那道题全班只有我和另外两个人做出来了..我只是个初一学生...先分别相乘得xy-5y+2x-10=xy移项消去xy得-

(*^__^*)嘻嘻……自己慢慢想吧!用计算器算呗

1/x-1/y=4则：1/y-1/x=-4所以：2x-3xy-2y/2xy-x+y分子分母同除以xy得：原式=[2(1/y-1/x)-3]/[2-(1/y-1/x)]=(-8-3)/(2+4)=-11