若x^2-y^2=12,x y=6,求x,y的值-搜答案-大师作文网

即x=y=1xy=1对不对?如果对的话x^2+2y^2-2xy-2y+1=0化简为你做的很对.就是这样解的,没有其他更好的方法了.这里用到的是数学里的

(-3x^y+2xy)-(4x^+xy)=-3x^y+2xy-4x^-xy=-3x^y+xy-4x^所以填上-3x^y+xy-4x^

提出-6xy,原式=-6xy（x-2y）=-6*1*3=-18

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

因为x+2y=0,所以x=-2y原式=(x^2+2xy)/(xy+y^2)=(4y^2-4Y^2)/(-3y^2+y^2)=0/(-2y^2)又因为xy不等于零,所以x、y君不等于零,所以-2y^2亦

（4xy+12y)+[7x-(3xy+4y-x)]=4xy+12y+7x-3xy-4y+x=xy+8x+8y=xy+8(x+y)=(-2)+8*3=-2+24=22

(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)=-2xy+2x+3y-3xy-2y+2x-x-4y-xy=-6xy+3x-3y=-6xy+3*(x-y)当时,原式=-6*1+3*

x+2y=0,xy不等于0∴x=-2yx²+2xy/xy+y²=(4y²-4y²)/(-2y²+y²)=0

2x+y+6=xy化简得：Y=(2X+6)/(X-1)X不等于0因为正实数x.所以X>0所以X>1函数Y=(2X+6)/(X-1)是单调递增所以X=2为最小值,Y=10所以XY最小值为XY=20

x^2+2xy-3y^2=0x^2+2xy+y^2-4y^2=0(x+y)^2=4y^2x+y=2y或x+y=-2yx=y或x=-3y因为两个正实数所以x=yx^2+xy+y^2/x^2-xy+y^2

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

x^2-xy+y^2＝x^2+2xy+y^2-3xy＝（x+y）^2-3xy=7^2-3x12=49-36=13

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-(

(x+y)²=x²+2xy+y²=(x²-2xy+y²)+4xy=(x-y)²+4xy=49所以x+y=±7x²y+xy²

x(x²+xy+y²)-y(x²+xy+y²)+3xy(y-x)=X^3+X^2Y+XY^2-X^2Y-XY^2-Y^3+3XY^2-3X^2Y=X^3-3X^

（Y－X）÷（XY）＝3可变形为Y-X=3XY（2X＋3XY－2Y）÷（X－2XY－Y）=(2X-2Y+3XY）÷(X-Y-2XY)={2（x-y)+3xy}÷(X-Y-2XY)={2(3xy)+3x

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^2+3xy+2y^2)÷(x^2y+2xy^2)=(x+2y)(x+y)/xy(x+2y)=(x+y)/xy=12/9=4/3

x²-7xy+12y²=0(x-3y)(x-4y)=0x1=3yx2=4yx=3y时原式＝9y²-3y²+y²/6y²=7/6x=4y时原式

x^2y+xy^2＝xy×（x+y）＝6×5＝30