过圆x² y²-x y-2=0和x² y²=5的交点

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=

3x*+xy-2y*=0（3x-2y）(x+y)=0那么x=2y/3或x=-yy/x=3/2或x/y=-1(x/y)-(y/x)-(x*+y*)/(xy)=(x/y)-(y/x)-(x/y+y/x)=

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

y-x-2xy=0y-x=2xyx-y=-2xy(3x+xy-3y)/(y-xy-x)=[3(x-y)+xy]/[(y-x)-xy]=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5

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

(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

xy的最小值是64,此时x=16；y=4.2x+8y-xy=0得出2x+8y=xy;由于x与y都大于0,所以（2x+8y）≥8√xy;所以xy-8√xy=0时,xy有最小值；√xy（√xy-8）=0；

2X^2－XY－5X+Y+4=X^2+X(X-Y)-4X-X+Y+4=(X-2)^2+(X-1)(X-Y)=0x≥y≥1(x-2)^2>=0,x-1>=0,x-y>=0,即(x-1)(x-y)>=0两

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

实数x、y,满足x≥y≥1,2x^2-xy-5x+y+4=0,则2x^2-5x+4=(x-1)y≤(x-1)x,即2(x-2)^2≤0,x=2,y=2.

2x²-xy-5x+y+4=o(x²-4x+4)+(x²-xy-x+y)=0(x-2)²+(x-y)(x-1)=0因为x≥y≥1所以x-y≥0x-1≥0即(x-

3x^2+xy-2y^2=0推出(3x-2y)(x+y)=0推出x=-y或x=(2/3)y{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}/x^2-9y^2推出：{

即(x-2y)²=0x-2y=0所以x=2y所以原式=(2x²+2xy-xy-y²)/(4x²-4xy+y²)=(2x²+xy-y²

除3余2,加1除3整除除5余4,加1除5整除除7余6,加1除7整除除9余8,加1除9整除除11整除3、5、7、9最小公倍数是315315-1=314由于人数可以被11整除且314与11没有公约数所以总

y-x-2xy=0所以x-y=-2xyy-x=2xy所以原式=[3(x-y)+xy]\[(y-x)-xy]=[3×(-2xy)+xy]\(2xy-xy)=-5xy\xy=-5

lg(xy)=0xy=1则:|x|＝1而Y=X,|x|不等于Y所以x=-1,y=-1原式=log8（2）=1/3

解题思路：结合完全平方公式进行求解解题过程：答案见附件最终答案：略

7x^2-12xy+5y^2=0(7x-5y)(x-y)=07x=5y或x=y所以x/y=5/7或x/y=1x-y=x-7x/5=-2x/5或x-y=x-x=0即7x=5y时,x-y=-2x/5没有具

x+y=5xy（2x-3xy+2y)/(x+2xy+y）=[2（x+y）-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问：若x＋1/x＝3,求(x

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