二元二次方程组2x方 5xy-2y方=5

3x^2-y^2=8（1）x^2+xy+y^2=4（2）将2*(2)有2x^2+2xy+2y^2=8,与(1)连等2x^2+2xy+2y^2=3x^2-y^2,移项有x^2-2xy-3y^2=0用十字

我看懂了意思```但是解不一定正确我才读初1``题应该是：1.X+Y+1=0X^2+4*(Y^2)=82.(X-3)^2+Y^2=9X+2Y=03.(X^2)/5+(Y^2)/4=1Y=X-34.[(

x²-5xy+6y²＝0(x-2y)(x-3y)=0x=2y或x=3y1.x=2yx²+y²+x-11y-2＝04y²+y²+2y-11y-

x^2-2xy-3y^2=0（x-y）^2-4y^2=0（x-y）^2=(2y)^2x-y=±2yx-y=2y或x-y=-2yx1=3yx2=-y将x1,x2分别代入②,得：（3y）^2-y*3y+y

我不会打数学符号,只告诉你思路.2(x+y)^2+xy+(x+y)+1=0(x+y)^2+2xy+12(x+y)+10=0即{x+y=4{x+y=-2设a=x+yb=xyxy=-37xy=-11/3则

x^2+xy+y^2+x+5y=0,-----------(1)x+2y=0,x=-2y.代入方程（1）整理后得：y(3y-3)=0,y1=0,x1=0.y2=1,x2=-2.

|x+1|+(y-2)²=0|x+1|≥0(y-2)²≥0所以|x+1|=0,(y-2)²=0x=-1,y=23xy²-2(x²y-2xy)+5x&#

x^2+3xy+2y^2+4x+5y+3=(x+y)(x+2y)+3(x+y)+(x+2y)+3=(x+y)(x+2y+3)+(x+2y+3)=(x+y+1)(x+2y+3)

答：x=-1,y=2(3x²y-2xy²)-(xy²-2x²y)-(3x²y²+2x²y)-(-3x²y²-2

mx+4y=83x+2y=6得：x=4/(6-m)y=(14-3m)/(6-m)x的二次方=y的二次方[4/(6-m)]^2=[(14-3m)/(6-m)]^2m=10/3或6（舍去）

由y-x=1得y=x+1代入到2x^2-xy-2=0中得x²-x-2=0所以x=-1或x=2因此当x=-1时y=0当x=2时y=3所以{x=-1,y=0{x=2,y=3

x+y=-3x=-3-y带入xy=2(-3-y)y=2-y^2-3y-2=0y^2+3y+2=0(y+1)(y+2)=0y1=-1y2=-2x1=-2x2=-1

你的解法不对着...由（2）得：（x-2y）y=1（3）化解得：x=1/y+2y（4）把（4）代入（1）得到：（1/y+2y）方+（1/y+2y）-12=0化解得到：1/（y方）+6（y方）=7（5）

x2+y2+2xy=9(x+y)²=9x+y=3或-3(x-y)2-3x+3y+2=0(x-y)²-3(x-y)+2=0(x-y-1)(x-y-2)=0x-y=1或2所以组成4个方

原式=x²y(x-y)²-2xy(x-y)²=xy(x-y)²(x-2)再问：原式=x²y(x-y)²-2xy(y-x)²再答：对

x²-y²-x-y=0(x+y)(x-y)-(x+y)=0(x+y)(x-y-1)=0所以x+y=0或者x-y-1=0；4x²-y²+2y-1=04x²

(x+1)²+|y-1|=0两个非负数的和为0,这两个非负数都为0x+1=0,y-1=0x=-1,y=12(xy-5xy²)-(3xy²-xy)=2xy-10xy

x^2-xy+y^2=3,2x^2-xy-y^2=55x^2-5xy+5y^2=156x^2-3xy-3y^2=15两式子相减x^2+2xy-8y^2=0(x+4y)(x-2y)=0x=2y或者x=-

-2(xy-3y的二次方)-【2y的二次方-59xy-x的二次方)+2xy】=-2xy+6y²-2y²+5xy-5x²-2xy=xy+4y²-5x²=