消费XY,MUx=40-5x,MUy=30-y-搜答案-搜搜考试网

xy/x+y=3则xy=3(x+y)2x-5xy+2y/x-3xy+y=2(x+y)-5xy/(x+y)-3xy=2(x+y)-15(x+y)/(x+y)-9(x+y)=-13(x+y)/-8(x+y

10和50不过你的题目错了斜率应该是负值而不是正值

-xy（x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10

X-Y=5,XY=3.XY是多少?

Y=X-5XY=X²-5X=3X²-5X-3=0X=(5±√37)/2Y=X-5X=(5-√37)/2,Y=(-5-√37)/2X=(5+√37)/2,Y=(-5+√37)/2

在均衡点上,无差异曲线应当于预算线相切,切点斜率等于预算线斜率.设XY为两种商品均衡时的数量,预算线为2x+5y=270,这条线的斜率为-0.4.令dy/dx=-20/y=-0.4推出y=50,x=1

解(x+1)平方+/y-1/=0∴x+1=0,y-1=0∴x=-1,y=1∴2(xy-5xy平方)-(3xy平方-xy)=(2xy+xy)+(-10xy平方-3xy平方)=3xy-13xy平方=3×(

(8xy-3x平方)-5xy-2(3xy-2x平方)=8xy-3x²-5xy-6xy+4x²=x²-3xy=4+6=10

xy/(x+y)=2∴xy=2(x+y)(3xy-x-y)/(3x-5xy+3y)=[6(x+y)-x-y]/[3x+3y-10(x+y)]=5(x+y)/[-7(x+y)]=-5/7

x=-1,y=-6或x=6,y=1代入式子得x^2-xy^2=37或30x^2y+xy^2=-42或42

效用最大时有：MUX/PX=MUY/PY即20-x=(30-2y)/2此外,由收入约束可知：X*PX+Y*PY=I即x+2y=20联立方程,得：x=10,y=5

(x-xy)+(xy-y)=40-20x-xy+xy-y=20x-y=20(x-xy)-(xy-y)=40-(-20)x-xy-xy+y=60x+y-2xy=60

(5x-xy+5y)/(3xy-x-y)=[5(x+y)-xy]/[3xy-(x+y)]=[5(x+y)-2(x+y)]/[6(x+y)-(x+y)]=1/2

消费时候的最佳组合就是说两者MUx/Px=MUy/Py,这是一个式子.得X-Y+22=0,另一个条件是收入与消费,即Px*X+Py*Y=M,5X+Y-40=0,联立两式得,X=3.Y=25.

因为xy/（x+y）=1/2所以x+y=2xy原式=3（x+y)-5xy/(-x-y+3xy)=3*2xy-5xy/(-2xy+3xy)=xy/xy=1

X+y=3 xy=-5 Xy=?

X+y=3xy=-5X-y=?(x-y)^2=(X+y)^2-4xy=9+20=29则x-y=±根号29

3(x^2-xy)-xy+y^2=3(x^2-xy)-(xy-y^2)=3*5-(-3)=15+3=18

x^2-xy与xy-y^2相比各个式子提取公因式（x-y）求得x/y=3/2两个等式相加就是x^2-y^2=100因式分解（x+y）*（x-y）=100将x=3y/2带入求得y的平方是20可以x的平方

原式=-xy²（x²y^4-xy²-1）∵xy²=-2原式=2（（-2)²-（-2）-1）=10

x-y=(x-xy)+(xy-y)=40+(-20)=20x+y-2xy=(x-xy)-(xy-y)=60