已知代数式(ax by)(2x y)
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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
xy/x+y=3则xy=3(x+y)2x-5xy+2y/x-3xy+y=2(x+y)-5xy/(x+y)-3xy=2(x+y)-15(x+y)/(x+y)-9(x+y)=-13(x+y)/-8(x+y
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
x-y=2xy3x-5xy-3y/x+xy-y=[3(x-y)-5xy]/[(x-y)+xy]=(6xy-5xy)/(2xy+xy)=1/31/x+1/y=4y+x=4xyx-5xy+y/2x+xy+
-x的平方y-xy平方=-XY(Y+X),再把x+y=3,xy=2代入结果为=-XY(Y+X)=-2乘3=-6
∵x2-xy=7,2xy+y2=4,∴原式=(x2-xy)+(2xy+y2)=7+4=11,故答案为:11
原式=3xy+6y-xy+6x=2xy+6(x+y)=2*(-2)+6*4=24-4=20
原式=(3x+3y-xy)/[3xy-(x+y)]=[3(x+y)-xy]/[3xy-(x+y)]=[3-xy/(x+y)]/[3xy/(x+y)-1]=(3-2)/(3×2-1)=1/5
把已知两式相加结果为13
3(xy+2y)-(xy-6x)=3xy+6y-xy+6x=2xy+6(x+y)=2×(-2)+6×4=-4+24=20
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.
因为xy/(x+y)=1/2所以x+y=2xy原式=3(x+y)-5xy/(-x-y+3xy)=3*2xy-5xy/(-2xy+3xy)=xy/xy=1
x2+2xy-3y2=x2-xy+3xy-3y2=x2-xy+3(xy-y2),∵x2-xy=3,xy-y2=-5,∴x2+2xy-3y2=3+3×(-5)=-12.
(1)x²+4xy+3y²=x²+xy+3y²+3xy=(x²+xy)+3(y²+xy)=3-6=-3(2)x²-y²=
xy/(x+y)=2xy=2(x+y)(3x-5xy+3y)/(-x+2xy-y)=[3(x+y)-5xy]/[2xy-(x+y)]=[3(x+y)-10(x+y)]/[4(x+y)-(x+y)]=-
2x²-xy-3y²=2x²+2xy-3xy-3y²=2(x²+xy)-3(xy+y²)已知x²+xy=3,xy+y²=
x-y=(x-xy)+(xy-y)=40+(-20)=20x+y-2xy=(x-xy)-(xy-y)=60