求㏑√2x y的偏导-搜答案-智慧作业帮

由X+Y=3XY可得X+Y-XY=2XY,用X+Y-XY替换分母中的2XY,所以(2X+2Y-XY)/(X+Y+2XY)=(2X+2Y-XY)/(2X+2Y-XY)=1

y=3+xyy-xy=3y(1-x)=3y=3/(1-x)1)2x+3xy-2y/x-2xy-y=2x+xy-2y/x-y=2x+3x/(1-x)-6/x(1-x)-3/(1-x)=2x-3/(1-x

x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17

因为x/y=2所以x=2y是[x^2-xy+3y^2]/[x^2+xy+6y^2]吧=(4y^2-2y^2+3y^2)/(4y^2+2y^2+6y^2)=5y^2/12y^2=5/12

原式=2xy-6x-6y+3xy=5xy-6(x+y)=5×3-6×(-2)=27

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

因为x-y=4xy所以x-2xy-y=2xy2x+3xy-2y=11xyx-2xy-y分之2x+3xy-2y=5.5

x+y=3xy,所以2x+2y-xy/x+y+2xy=(2×3xy-xy)/(3xy+2xy)=5/5=1

3xy-[2xy-2(xy-2分之3xy)+xy]+3xy=6xy-[2xy-2xy+3xy+xy)=6xy-4xy=2xy=2×3×3分之1=2

x=-1y=-2或x=-2y=-1-2（xy-3x）-2（2y-xy）=-2（xy-3x+2y-xy）=-2（2y-3x）等于2或-8

这个是原题要求的吧|x|/x+|y|/y+|xy|/xy（1）xy>0x,y都大于零或都小于零x,y都大于零时|x|/x+|y|/y+|xy|/xy=|x|/x+|y|/y+|xy|/xy=x/x+y

-xy(x²y的五次方-xy的三次方-y)=-x³y的6次方+x²y的4次方+xy²=-（xy²）³+（xy²）²+xy

你只要X看成是是常数求导就行了,答案就不给你了,自己动手丰衣足食

解两边求导y‘cosy+e^x-y^2-2xyy'=0即y’(cosy-2xy)=y^2-e^xy'=(y^2-e^x)/(cosy-2xy)或者F(x,y)=siny+e^x-xy^2=0Fx=e^

分析：先求出未知多项式的表达式,再用它去减(xy-2xy)即可.令要求的多项式为a,依题意有：a+xy-2xz=3xz-xy将等式左边的多项式移到等式右边(移项的同时,要记得变号）,得：a=3xz-x

3/5再问：详细过程呢再答：y-x=3xyx-y=-3xy代入得：(-6xy+3xy)/(-3xy-2xy)=-3/-5=3/5

dx/dy-3xy=xy^2dx/x=(y^2+3y)dy两边积分得：lnx=y^3/3+3y^2/2+c==>x=exp(y^3/3+3y^2/2+c)=Cexp(y^3/3+3y^2/2)C常数

4种x=-3,y=4x=-1,y=4x=1,y=-4x=3,y=-4

x^2-xy=14,(1)xy-y^2=-11,(2)(1)-(2)得：x^2-2xy+y^2=14-(-11)=25

∵x-y/xy=3∴x-y=3xy2x+3xy-2y/x-2xy-y=[2(x-y)+3xy]/[(x-y)-2xy]=(6xy+3xy)/(3xy-2xy)=9xy/(xy)=9