2 3x-y减四分之x y等于负1 12,x y的三倍减2x减y的二倍等于三.-搜答案-智慧作业帮

x²+xy=2xy+y²=-1两式相减得：x²-y²=3两式相加得：x²+2xy+y²=1

xy分之x加y等于2∴x+y=2xy3x减5xy加3y分之负x加3xy减y=[-(x+y)+3xy]/[3(x+y)-5xy]=(-2xy+3xy)/(6xy-5xy)=xy/(xy)=1

由　1/X-1/Y=5,两边同乘　XY,得出Y-X=5XY,那么　　分子　-X+XY+Y=6XY分母　2X+7XY-2Y=7XY-2(Y-X)=-3XY　　得此分式的值为－2

3x^2y-xy^2=xy(3x-y)将x=-1/2y=1代入有-1/2*1*[3*(-1/2)-1]=-1/2*(-5/2)=5/4

1/x-1/y=2(-x+xy+y)/(2x+7xy-2y)=(-x+xy+y)÷xy/(2x+7xy-2y)÷xy=(-1/y+1+1/x)/(2/y+7-2/x)=(1/x-1/y+1)/[-2(

x分之(x-y)÷[x-x分之(2xy-y²)]=x分之(x-y)÷[x分之(x²-2xy+y²)]=x分之(x-y)*[(x-y)²分之x]=(x-y)分之1

稍等再问：在再答：正在做再答：不好意思再问：哦再答：x-4yx=-4yx-4xy+4y=0(x-2y)=0∴x-2y=0∴x=2y∴原式=(2y+4y)/(2y+y)=6/3=2再答：懂了吗再问：ok

绝对算不出来再答：如果是一道题发图咯再问：x平方减xy加y平方分之x平方加2xy加y平方他给你条件是y分之x等于2分之1xy再问：吧xy无视掉再答：马上再答：化成Y等于2X在带入再问：然后怎么样再答：

解析：

x分之1减y分之1等于2（y-x）xy=2y-x=2xyy减xy减x分之3x加xy减3y=[3(x-y)+xy]/(y-x-xy)=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5

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

x分之一减y分之一等于2分之1所以xy分之y-xy分之x=2分之1,xy分之（y-x）=2分之1,y-x=2分之xy,x-y=负2分之xy,所以x减y分之xy=（负2分之xy）分之xy=-xy分之（2

x^2-2xy+y^2+y^2-y+1/4=0(x-y)^2+(y-1/2)^2=0(x-y)^2>=0(y-1/2)^2>=0(x-y)^2+(y-1/2)^2>=0(x-y)=0(y-1/2)=0

1/x-1/y=3y-x=3xyx-y=-3xy(5x-xy-5y)/(x-xy-y)=(-15xy-xy)/(-3xy-xy)=4

悬赏分给我

x分之1减y分之1等于31/x-1/y=3(y-x)/xy=3y-x=3xy所以x-xy-y分之5x-xy-5y=（-3xy-xy）分之(-15xy-xy)=-4分之（-16）=4

由已知条件可得：x-y=-4xy,（也就是在等式两边乘xy后整理,即可）,代入所求的式子里分母为-4xy+7xy,即3xy；分子为-4xy-2xy,即-6xy,化简得-2

已知xy/(x+y)=2,求:(3x-5xy+3y)/(-x+3xy-y)xy/(x+y)=2得：xy=2(x+y)(3x-5xy+3y)/(-x+3xy-y)=(3x-9xy+3y+4xy)/(-x

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x=2/3,y=-3/4,then?