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化简:(1)2(x2-2xy)-3(y2-3xy);(2)2a-[3b...

(1)原式=2x2-4xy-3y2+9xy=2x2+5xy-3y2;(2)原式=2a-(3b-5a-3a+5b)=2a-3b+5a+3a-5b=10a-8b;(3)原式=-x2+2xy-y2-2xy+6x2+6x2-3xy=-11x2-3xy-y2.

(1)①A+B+C=x2-3xy+y2-2xy-x2+2y2=-5xy+3y2;②2A-B-2C=2(x2-3xy)-(y2-2xy)-2(-x2+2y2)=2x2-6xy-y2+2xy+2x2-4y2=4x2-4xy-5y2;(2)2(3x2y-xy2)-(xy2+6x2y)+1=6x2y-2xy2-xy2-6x2y+1=-3xy2+1,∵|x-1|+(y+2)2=0,∴x=1,y=-2,则原式=-...

①原式=3x2-6xy-3x2+2y+6xy+2y=4y;②-B+2A=-(2ab-3b2+4a2)+2(3a2+b2-5ab)=-2ab+3b2-4a2+6a2+2b2-10ab=2a2+5b2-12ab;当a=-12,b=2时,-B+2A=2×(?12)2+5×22-12×(-12)×2=12+20+12=3212.

x2-2(x2-3xy)+3(y2-2xy)-2y2=x2-2x2+6xy+3y2-6xy-2y2=-x2+y2,当x=12,y=-1时,原式=-(12)2+(-1)2=-14+1=34.

(1)原式=2x2y-2xy2+3x2y2-3x2y2-3x2y2+3xy2=2x2y+xy2-6x2y2,当x=-1,y=2时,原式=4-4-24=-24;(2)原式=12a2b-4ab2+5ab2-5a2b-2a2b-12=5a2b+ab2-12,∵(15-a)2+|b-5|=0,∴a=15,b=5,则原式=1+5-12=-6.

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

(1)原式=4a2+18a-9a2-12a+3=-5a2+6a+3;(2)原式=3x2-6xy-9x2+6y-6xy-6y=-6x2-12xy,当x=12,y=-34时,原式=-32-6×34=-20512.

(1)3x3-1-3x-5+4x-2x3=(3x3-2x3)+(-3x+4x)+(-1-5)=x3+x-6.(2)3x2y3+2xy?7x2y3?32xy+2+4x2y2.=(3x2y3-7x2y3)+(2xy-32xy)+4x2y2+2=-4x2y3+12xy+4x2y2+2.

(1)原式=x?y(x?y)2-x(x+y)(x+y)(x?y)=1x?y-xx?y=1?xx?y,∵(x-2)2+|y-3|=0,∴x=2,y=3,则原式=1?22?3=1;(2)联立得:x?1<0①2x+3>1②,由①得:x<1,由②得:x>-1,则不等式组的解集为-1<x<1,表示在数轴上,如图所示:

1. 化简代数式的结果为:xy+8(x+y)=1+3*8=25 2. 化简代数式的结果为:4b-a=-4-1/2=-4.5 3. x^2+ax+7-(bx^2-2x+9y-1)=(1-b)x^2+(a+2)x-9y+8 因为差值与字母x的取值无关 故有 1-b=0 ,a+2=0 解得b=1,a=-2 所以(2a+3b)^2013=(-2*2+3)^2013=-1 二...

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