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(1)化简:4xy-(3x2-3xy)-2y+2x2(2)(a+b)-2...

(1)原式=4xy-3x2+3xy-2y+2x2=7xy-x2-2y;(2)原式=a+b-4a+6b+3a-2b=5b;(3)原式=-13x-23y+23y=-13x,当x=6,y=-1时,原式=-2;(4)原式=(2-2b)x2+(a+3)x-6y+5,∵代数式的值与字母x的取值无关,∴2-2b=0且a+3=0,∴a=-3,b=1,∴ab=(-3)...

(1)2x2-3x-1+4x-3x2=-x2+x-1;(2)∵A=3x-2y,B=x-3y+1,∴3(A+B)-2(2A-B)=3A+3B-4A+2B=-A+5B=-(3x-2y)+5(x-3y+1)=-3x+2y+5x-15y+5=2x-13y+5.

(1)原式=3xy+3x2+2y-3xy-2x2=x2+2y,当x=-2,y=1时,原式=4+2=6;(2)根据题意得:a+b=0,cd=1,m=3或-3,当m=3时,原式=0+9-3+15=21;当m=-3时,原式=0+9-3-15=-9.

(1)原式=4x2,将x=-12代入得:原式=1.(2)∵A=2x2+4xy-2x-3,B=-x2+xy+2∴3A=3(2x2+4xy-2x-3)=6x2+12xy-6x-9,∴6B=6(-x2+xy+2)=-6x2+6xy+12,∴3A+6B=(6x2+12xy-6x-9)+(-6x2+6xy+12)=6x2+12xy-6x-9-6x2+6xy+12=18xy-6x+3=6x(3y-1)+3...

解答:(1)解:原式=3x2-[2x2y-xy+x2]+4x2y,=3x2-2x2y+xy-x2+4x2y,=2x2+2x2y+xy,(2)解:原式=x2+4xy+4y2-(3x2+2xy-y2)-5y2,=x2+4xy+4y2-3x2-2xy+y2-5y2,=-2x2+2xy,当x=-2,y=12时,原式=?2×(?2)2+2×(?2)×12,=-8-2,=-10.

解答:(1)原式=4x2+12x+9-9x2-12x-4=-5x2+5;(2)原式=4a2(a2-b2)-4a2+b2=4a4-4a2b2-4a2+b2(3)20012=(2000+1)2=4000000+4000+1=4004001;(4)原式=-12×?(-a)5=a52;(5)原式=[(x-z)-y](x+y-z)=(x-z)2-y2=x2-2xz-z2-y2;(6)...

(1)原式=-2x-4x+2y+3x-2y+1=-3x+1,当x=-3时,原式=10;(2)原式=xy-2y2-8xy+6y2-2x2y+30y2-4x2y=-7xy+34y2-6x2y,当x=1,y=-2时,原式=162.

解:(1)原式=4y;(2)原式=2a 2 -12ab+5b 2 当a=- ,b=2时,原式=32.5。

为了表述方便,首先定义:x^2为x的平方,换言之^左为底数,右侧为幂; *为乘号 解: 对右侧用公式,设3x=a,2y=b,则[(3x+2y)^2-(3x-2y)^2]=4ab=4*(3x)*(2y)=24xy; (2x+3y)(2x-3y)=4x^2-9y^2 所以原式可化简为:48x^3y-108xy^3

(1)-( x2+y2)-[3xy+( x2-y2)]=-x2-y2-( 3xy+x2-y2)=-x2-y2-3xy-x2+y2=(-1-1)x2+(-1+1)y2-3xy=-2x2-3xy;∵x=1,y=-2,∴上式=-2×12-3×1×(-2)=-2+6=4.(2)∵3(A+B)-2(2A-B)=3A+3B-4A+2B=-A+5B,∴-A+5B=-(3x-2y?)+5(x-3y+1?)...

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