已知x y=2,xy=-3,求2(xy-3x)-3(2y xy)的值-搜答案-大师作文网

y=3+xyy-xy=3y(1-x)=3y=3/(1-x)1)2x+3xy-2y/x-2xy-y=2x+xy-2y/x-y=2x+3x/(1-x)-6/x(1-x)-3/(1-x)=2x-3/(1-x

x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17

xy^2*(-x^2y^2)*（1/2xy^3)^2=xy^2*(-x^2y^2)*（1/4x²y^6)=xy^2*(x^4y^8)*(-1/4)=(-1/4)*xy²*(xy&#

x2-xy=-3①，2xy-y2=-8②，①×2+②×3得：2x2-2xy+6xy-3y2=-6-24=-30，则2x2+4xy-3y2=-30．

因为x/y=2所以x=2y是[x^2-xy+3y^2]/[x^2+xy+6y^2]吧=(4y^2-2y^2+3y^2)/(4y^2+2y^2+6y^2)=5y^2/12y^2=5/12

原式=2xy-6x-6y+3xy=5xy-6(x+y)=5×3-6×(-2)=27

-xy（x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10

原式=3xy+6y-xy+6x=2xy+6(x+y)=2*(-2)+6*4=24-4=20

解(x+1)平方+/y-1/=0∴x+1=0,y-1=0∴x=-1,y=1∴2(xy-5xy平方)-(3xy平方-xy)=(2xy+xy)+(-10xy平方-3xy平方)=3xy-13xy平方=3×(

x=-1y=-2或x=-2y=-1-2（xy-3x）-2（2y-xy）=-2（xy-3x+2y-xy）=-2（2y-3x）等于2或-8

1、已知2x²+xy=10,3y²+2xy=6,求4x²+8xy+9y²的值为?分析：通过观察,可以把8xy拆成2xy+6xy,分别于剩余的两项组合,并提取公因

答案是3/2你是不是把分母打错了教你个方法因为上下是齐次的直接令x=3y=2带入就行

3（xy+2y）-（xy-6x）=3xy+6y-xy+6x=2xy+6(x+y)=2×(-2)+6×4=-4+24=20

3/(x-y)=1/xyx-y=3xyy-z=-3xy原式=[(y-x)-2xy]/[2(x-y)+3xy]=[(-3xy)-2xy]/[2(3xy)+3xy]=-5xy/9xy=-5/9

因为y=3xy+x，所以x-y=-3xy，当x-y=-3xy时，2x+3xy−2yx−2xy−y＝2(x−y)+3xy(x−y)−2xy＝2(−3xy)+3xy−3xy−2xy＝35．

3xy=2x+3y+5(3y-2)(x-1)=7所以3y-2=7x-1=1得y=3x=2xy=6或3y-2=1x-1=7得y=1x=6xy=6所以xy=6

∵x-y/xy=3∴x-y=3xy2x+3xy-2y/x-2xy-y=[2(x-y)+3xy]/[(x-y)-2xy]=(6xy+3xy)/(3xy-2xy)=9xy/(xy)=9

2x²-xy-3y²=2x²+2xy-3xy-3y²=2(x²+xy)-3(xy+y²)已知x²+xy=3,xy+y²=

原式=-xy²（x²y^4-xy²-1）∵xy²=-2原式=2（（-2)²-（-2）-1）=10