已知x y=a xy=b 则xy^2 yx^2=
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x^2+Axy-xy^2与3xy-Axy^2-y^3的和不含xy项,所以A=-3;和为x^2+2xy^2-y^3
1:已知多项式x^2+2axy-xy^2与多项式3xy-axy^2-y^3的和不含xy项所以2a=-3a=-3/2x^2+2axy-xy^2+3xy-axy^2-y^3=x^2-xy^2+1/2xy^
A-2B=5x²-3xy²+2xy-2(7xy²-2xy+x²y)=5x²-3xy²+2xy-14xy²+4xy-2x²
∵2(x2+xy)-3(xy+y2)=2x2-xy-3y2,∴2x2-xy-3y2=2×3-3×(-2)=12.故选A.
1.其和为(x²+xy²/2-y³)2.e的值是(-6)3.证明(见下面详细过程)1.∵x²+2axy-xy²与3xy-axy²-y
(1)∵xy+x=-1①,xy-y=-2②,∴①-②得x+y=1;(2)先把xy+x=-1,xy-y=-2的值代入代数式,得原式=-x-[2y-1+3x]+2[x+4]=-x-2y+1-3x+2x+8
X^2+AXY-XY^2+3XY-AXY^2-y^3=X^2+(A+3)XY-(A+1)XY^2-y^3不含XY项,所以A+3=0A=-3所以和=X^2+2XY^2-y^3
∵x2+xy=2,y2+xy=5,∴x2+2xy+y2=7,则原式=12(x2+2xy+y2)=72,故答案为:72
xx+2xy-yy=-3两式相加即可
x平方+2axy-xy平方+3xy-axy平方-y三次方=x平方+2axy+3xy-axy平方-xy平方-y三次方=x平方+(2a+3)xy-(a+1)xy平方-y三次方不含xy项即2a+3=0a=-
a-2b=(5x²y-3xy²+4xy)-2(7xy²-2xy+x²y)=5x²y-3xy²+4xy-14xy²+4xy-2x
是同类型则x和y的次数相同所以1=b1-c=6b=1,c=-5系数是2a-4=-2a=1所以a-b-c=5
=11-c=62a-4=-2∴a=1b=1c=-5∴a-b-c=1-1-(-5)=5
有x2+xy=3可得,2x2+2xy=6 (1),有xy+y2=-2得,3xy+3y2=-6 (2),根据分析,(1)-(2)可得,2x2-xy-3y2=6-(-6)=
∵x-y=4xy,∴2x+3xy-2yx-2xy-y=2(x-y)+3xyx-y-2xy=8xy+3xy4xy-2xy=112.故答案为:112.
∵A=8x²y-6xy²-3xy,B=7xy²-2xy+5x²y ∴C=3(A+B) =3(8x²y-6xy²-3xy+7xy²
已知A=5x^2y-3xy^2+4xy,B=7xy^2-2xy+x^2y.(1)求A-2B的值A-2B=5x^2y-3xy^2+4xy-2*(7xy^2-2xy+x^2y)=5x^2y-3xy^2+4
5xy^2+axy^b=-2xy^b5xy^2=(-2-a)xy^b对比方程左右两边:首先知道方程左边不恒为0,因此两边的未知数幂的次数有各自对应关系.常数项对应常数项.即:2=b5=-2-aa=-7