14(x y)=28020(x-y)=280结算

x²+xy+y²-（x²-xy+y²）=2xy=14-28=-14,xy=-714=x²+xy+y²+xy-xy=x²+2xy+y

x^2+xy+y=14,y^2+xy+x=28两式相加得x²+2xy+y²+(x+y)=42(x+y)²+(x+y)-42=0(x+y+7)(x+y-6)=0所以x+y+

1.2(Xy+Xy)-3(Xy-xy)-4Xy=2*2xy-0-4xy=4xy-4xy=02.1/2ab-5aC-(3acb)+(3aC-4aC)=1/2ab-5ac-3acb-ac=1/2ab-6a

x^2+xy+y=14y^2+xy+x=28+x^2+2xy+y^2+x+y=42(x+y)^2+(x+y)=42(x+y)(x+y+1)=0则x+y=0或x+y=-1

x²+xy+y²=14,x²-xy+y²=28相加2(x²+y²)=42x²+y²=21相减2xy=-14所以(x+y)

题有问题吧,是X+XY+Y=14吧?如果是的话x+xy+y+y+xy+x=42合并一下（X+Y）+x+y=42设x+y=a则a+a=42a=6或a=-7

x^2+xy+y=14y^2+xy+x=28两式相加x^2+y^2+2xy+x+y=42(x+y)^2+(x+y)-42=0(x+y-6)(x+y+7)=0x+y=6或x+y=-7

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

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

y-x=3xyx-y=-3xy(x-2xy-y)/(2x-14xy-2y)=(-3xy-2xy)/(-3xy*2-14xy)=-5xy/(-20xy)=1/4

∵y-x=3xy∴x-y=-3xy∴(2x-14xy-2y)/(x-2xy-y)=[2(x-y)-14xy]/[(x-y)-2xy]=(-6xy-14xy)/(-3xy-2xy)=(-20xy)/(-

此题主要是把x-y用-3xy代替就可作了x-2xy-y/2x-14xy-2y=(-3xy-2xy)/2(x-y)-14xy=-5xy/(-6xy-14xy)=-5xy/-20xy=1/4

2(x+xy)-[(xy-3y)-x]-(-xy)=2x+2xy-xy+3y+x+xy=3x+3y+2xy=3（x+y）+2xy=3*（-2）+2*3=0

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

(3x^2+2xy)/xy-(2x^2-xy)/xy=(3x^2+2xy-2x^2+xy)/xy=(x^2+3xy)/xy=x(x+3y)/xy=(x+3y)/y

那个2后面应该是y吧,直接化简呀,展开后得：2.5xy+10y+6x-2xy+y+5x=0.5xy+11x+11y=0.5xy+11(x+y)=0.5*14+11*(-7)=-70

(2x-14xy-2y)除以(x-2xy-y)=4(2x-14xy-2y)=4(x-2xy-y)2x+6xy-2y=0x-y=-3xy两边同除以xy,得1/y-1/x=-3所以1/x-1/y=3

x^2-xy=14,(1)xy-y^2=-11,(2)(1)-(2)得：x^2-2xy+y^2=14-(-11)=25

由xy+x=16,得x=16/(y+1)代入xy-x=8,得16y/(y+1)-16/(y+1)=8=>16(y-1)/(y+1)=8=>(y-1)/(y+1)=1/2移项,通分得y-3/2(y+1)

∵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