已知xy =1,求代数式-3
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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
绝对值大于等于0,相加等于0,若有一个大于0,则另一个小于0,不成立所以两个都等于0所以x+y+1=0xy+3=0xy=-3x+y=-1两边平方x^2+2xy+y^2=(-1)^2x^2+y^2=1-
(xy+5x-2y)-(-3xy+2x-5y)=xy+5x-2y+3xy-2x+5y=4xy+3x+3y=4xy+3(x+y),当x+y=1,xy=-2时,原式=4×(-2)+3×1=-8+3=-5.
xy/x+y=3xy=3(x+y)3x-5xy+3y/-x+3xy-y=(3x+3y)-5*3(x+y)/[-x-y+3*3(x+y)]=-12(x+y)/8(x+y)=-3/2望采纳,谢谢!
解x+2y=2xy=12x+4y+3xy+1=2(x+2y)+3×1+1=2×2+3+1=4+4=8
-5再问:过程再答:
5xy+4x+7y+6x-3xy-4xy+3y=5xy-3xy-4xy+4x+6x+7y+3y=(5-3-4)xy+(4+6)x+(7+3)y=-2xy+10x+10y=-2xy+10(x+y)因为x
∵(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
2(x+y)=-6x+y=-3(x+2)-(3xy-y)=x+2-3xy+y=x+y+2-3xy=-3+2-3=-4
代数式可化为2x+2xy-xy+3y+x+xy=3x+3y+2xy=3(x+y)+2xy=3×(-2)+6=0a^2-b^2=15 a^2-2ab+b^2=5&nbs
x=-1y=2代入求值就可以
原式=-2x^2-2y^2-3xy-11xy=-2*7-14*(-1)=0
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.
5x^2-(3xy+4y^2)-(11xy-2y^2)-7x^2=5x^2-3xy-4y^2-11xy+2y^2-7x^2=-2x^2-2y^2-14xy=-2(x^2+y^2)-14*xy=-2*7
(5x+xy-5y)/(x-xy-y)=(5/y+1-5/x)/(1/y-1-1/x)=(1-3)/(-1-3)=1/2
∵|x+y+1|≥0,|xy-3|≥0|x+y+1|+|xy-3|=0,∴x+y+1=0,即x+y=-1xy=3xy3+x3y=xy(x²+y²)=yx[(x+y)²-2
(1)x²+4xy+3y²=x²+xy+3y²+3xy=(x²+xy)+3(y²+xy)=3-6=-3(2)x²-y²=
xy/x+y=3xy=3(x+y)3x-5xy+3y/-x+3xy-y=3x-15(x+y)+3y/-x+9(x+y)-y=-12(x+y)/8(x+y)=-3/2
2x²-xy-3y²=2x²+2xy-3xy-3y²=2(x²+xy)-3(xy+y²)已知x²+xy=3,xy+y²=