若xy满足3分之X 1=2分之Y 2=2分之X Y

若x平方-2xy+y平方-x+y-3=0求x-y的值(X-Y)(X-Y)-(X-Y)=3解下就可以了解之得:X-Y=1/2+根号13/2或者1/2-根号13/2已知实数x,y满足x平方+xy-y平方=

1/x+1/y=2则(2x+3xy+2y)/(x-xy+y)分子分母同除以xy=(2/x+2/y+3)/(1/x+1/y-1)=(4+3)/(2-1)=7

xy/(x+y)=2解得xy=2(x+y)所以(3x-5xy+3y)/(-x+3xy-y)=(3/2*xy-5xy)/(-1/2*xy+3xy)=-7/5

x/y=3x=3y(x²+2xy-3y²)/(x²-xy+y²)=(9y²+6y²-3y²)/(9y²-3y²

xy/3=-2u=-6/x所以是反比例函数

xy=6/(x+y)xy(x+y)=6,已知x和y是整数,则xy和(x+y)也是整数,而6=2*3=1*6当xy=3时,x+y=2,无整数解当xy=1时,x+y=6,无整数解当xy=6时,x+y=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

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

因为X+Y分之XY=2,所以XY=2(X+Y)代入后面的分子式得：13（X+Y)/5(X+Y)=13/5

x^2+y^2+5/4=2x+y(x-1)^2+(y-1/2)^2=0x=1,y=1/2xy/(x+y)=1*(1/2)/(1+1/2)=1/3

【x+y】分之xy=-2,xy分之【x+y】=-1/21/x+1/y=-1/2(1)【y+z】分之yz=3分之4,yz分之【y+z】=3/41/y+1/z=3/4(2)【z+x】分之zx=-3分之4,

（x+2y-3xy)-(-2x-y+xy)=x+2y-3xy+2x+y-xy=(1+2)x+(2+1)y-(3+1)xy=3x+3y-4xy=3(x+y)-4xy=3*1/2-4*(-1/2)=3/2

原式=(2x-4xy-2y+xy)/(x-2xy-y)=2+xy/(x-2xy-y)xy/(x-2xy-y)的倒数等于1/y-2-1/x=-5,所以xy/(x-2xy-y)=-1/5,原式=2-1/5

x-y分之xy=-3分之1xy分之(x-y)=-3x-y=-3xyx-2xy-y分之2x+3xy-2y=(-6xy+3xy)/(-3xy-2xy)=3/5

当直线与圆相切时,斜率最大

已知xy满足x²+y²+5/4(四分之五)=2x+y,求代数式(x+y)xyx²+y²+5/4=2x+yx²-2x+1+y²-y+1/4=0

xy/(x+y)=2(x+y)/xy=1/21/x+1/y=1/2(3x-xy+3y)/(-x+3xy-y)=(3/y-1+3/x)/(-1/y+3-1/x)=[3(1/x+1/y)-1]/[(3-(

1/x-1/y=3(y-x)/xy=3y-x=3xy分式的分母=x-2xy-y=(x-y)-2xy=-5xy分子=2x+3xy-2y=2(x-y)+3xy=-3xy所以原式=3/5

x^2-y^2=2xy,得x/y-y/x=2,即（y/x)^2+2(y/x)-1=0∴y/x=-1+√2或y/x=-1-√2(舍去,因为x,y都是正数).即（x-y)/(x+y)=√2-1

1/x-1/y=3(y-x)/xy=3y-x=3xy所以x-y=-3xy原式=[2(x-y)+3xy]/[(x-y)+2xy]=[2(-3xy)+3xy]/[(-3xy)+2xy]=-3xy/(-xy