已知A=x²-2xy,B=y²-3xy,求2A-3B
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A-2B=2x²+3xy+2y-1-2(x²-xy+x-1/2)=2x²+3xy+2y-1-2x²+2xy-2x+1=5xy-2x+2y=x(5y-2)+2y根
A=4x²+2xy+y²,B=x²+xy-5y²,A-2B=4x²+2xy+y²-2(x²+xy-5y²)=4X^2+6
(1)A-B=2x^2-3xy+2y^2-(x^2+xy-3y^2)=2x^2-3xy+2y^2-x^2-xy+3y^2=x^2-4xy+5y^2(2)2A-3B+C=0即:2(2x^2-3xy+2y
A-2B=5x²-3xy²+2xy-2(7xy²-2xy+x²y)=5x²-3xy²+2xy-14xy²+4xy-2x²
x^2-3xy+4y^2=(x^2+xy)+4(y^2-xy)=a+4
解2A-[B-(B-A)+2A+B]=2A-[B-B+A+2A+B]=2A-(B+3A)=-B-A=-(x²+2xy+y²-3)-(x²-2xy+y)=-x²-
∵A=4x²-4xy+y²B=x²+xy-5y²∴(3A-2B)-(2A+B)=3A-2B-2A-B=A-3B=4x²-4xy+y²-3(x
解∵2x²+xy=a∴4x方+2xy=2a----------(1)3y²-2xy=b∴9y方-6xy=3b-----------(2)(1)-(2)得:4x方+8xy-9y方=2
再问:-ab(a-b)²+a(b-a)²-ac(a-b)²再答:
(1)x=y=-2时,A=2×(-2)^3+3×(-2)×(-2)+2×(-2)-1=-9,B=(-2)^2-(-2)×(-2)+(-2)-1/2=-5/2A-2B=-9+5=-4(2)A-2B=2x
A-2B=(4x²+xy+y²)-2(x²+xy-5y²)=4x²+xy+y²-2x²-2xy+10y²=2x²
解题思路:题不完整,请补充解题过程:.最终答案:略
已知A=4x²-4xy+y²,B=x²+xy-5y²则,A-3B=4x^2-4xy+y^2-3(x^2+xy-5y^2)=4x^2-4xy+y^2-3x^2-3
a-2b=(5x²y-3xy²+4xy)-2(7xy²-2xy+x²y)=5x²y-3xy²+4xy-14xy²+4xy-2x
A+B=(x²-3xy+y²)+(2x²+xy-9y²)=x²-3xy+y²+2x²+xy-9y²=3x²-2
因为2(x-1/2)²+|y-1|=0所以x-1/2=0且y-1=0x=1/2,y=1所以3B-2A=3(2x²-3xy-2y²)-2(3x²-xy+y
4x²+8xy+9y²=2x²+2x²+xy+xy+6xy+9y²=2a+9y²+6xy=2a+3y²+2xy+3y²+
1.首先分析可以得出X≠0,XY≠0所以√xy-1=0即XY=1所以可得出X=|x|,xy=y,解得x=1,2y=2或者x=y,xy=|x|,解得x=-1,2y=-22.你的题目应该有问题,如果是A包
∵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