2x y-3=0化成用x的代数式表示y-搜答案-智慧作业帮

3x+2y=43x=4-2yx=4/3-2/3y5x-3y=41Y=X则5X-3X=4X=2Y=22Y=-X则5X+3X=4X=1/2Y=-1/2

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

21/5

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

由y=3xy+x得x-y=-3xy2x+5xy-2y/x-2xy-y=2（x-y）+5xy/x-y-2xy=-6xy+5xy/-3xy-2xy1/5

-5分之2

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

已知x+3xy-y=0则x-y=-3xy所以x-2xy-y分之2x-14xy-2y=[(x-y)-2xy]/[2(x-y)-14xy]=[-3xy-2xy]/[2*(-3xy)-14xy]=(-5xy

x^2-3xy+4y^2=(x^2+xy)+4(y^2-xy)=a+4

原式=6x+4xy+2xy+3x+2y-4xy+7y=9x+9y+2xy=9(x+y)+2xy=9×4+2×2=36+4=40

∵(x+1)²+|y+2|=0∴要使等式成立,则x+1=0且y+2=0即x=-1,y=-2∴5xy-3/2x³y²-4xy+1/2y²x³-1/2xy

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

(3xy+2)^2+|7-x-y|=0,则3xy+2=0,7-x-y=0,即x+y=7,xy=-2/3(5xy+10y)-[-5x-(4xy-2y+3x)]=5xy+10y-(-5x-4xy+2y-3

x+3xy-y=0∴x-y=-3xy2x-14xy-2y/x-2xy-y=[(2x-2y)-14xy]/[(x-y)-2xy]=[2(x-y)-14xy]/[(x-y)-2xy]=(-6xy-14xy

解题思路：先合并同类项，再结合已知条件变形，代入数值进行计算解题过程：求代数式(2x+3y-2xy)-(x+4y+xy)-（3xy+2y-2x）的值解：(2x+3y-2xy)-(x+4+xy)-（3x

（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)]=-

∵x+3xy-y=0∴x-y=-3xy\x102x-14xy-2y/x-2xy-y\x10=[2(x-y)-14xy]/[(x-y)-2xy]\x10=(-6xy-14xy)/(-3xy-2xy)\x

∵x-y=4xy∴原式=[2(x-y)+3xy]/[-(x-y)-2xy]=(8xy+3xy)/(-4xy-2xy)=11xy/(-6xy)=-11/6