(1)化简(4x2﹣2x﹣1)﹣{5x2﹣[8x﹣2﹣3(x2+x)]﹣x2}(2)先化简,5abc﹣{2a2b﹣[3abc﹣(4ab2﹣a2b)]}+3ab2,其a=1,b=﹣1,c=﹣(3)已知(

题目简介

(1)化简(4x2﹣2x﹣1)﹣{5x2﹣[8x﹣2﹣3(x2+x)]﹣x2}(2)先化简,5abc﹣{2a2b﹣[3abc﹣(4ab2﹣a2b)]}+3ab2,其a=1,b=﹣1,c=﹣(3)已知(

题目详情

(1)化简(4x2﹣2x﹣1)﹣{5x2﹣[8x﹣2﹣3(x2+x)]﹣x2}
(2)先化简,5abc﹣{2a2b﹣[3abc﹣(4ab2﹣a2b)]}+3ab2,其a=1,b=﹣1,c=﹣
(3)已知(x﹣2)2+|xy﹣4|=0,先化简再求值.3x2y+{﹣2x2y﹣[﹣2xy+(x2y﹣4x2)﹣xy]+xy2}.
题型:计算题难度:中档来源:辽宁省期中题

答案

解:(1)原式=4x2﹣2x﹣1﹣{5x2﹣[8x﹣2﹣3x2﹣3x]﹣x2}=4x2﹣2x﹣1﹣{5x2﹣8x+2+3x2+3x﹣x2}=4x2﹣2x﹣1﹣5x2+8x﹣2﹣3x2﹣3x+x2=﹣3x2+3x﹣3
(2)原式=5abc﹣{2a2b﹣[3abc﹣4ab2+a2b]}+3ab2=5abc﹣{2a2b﹣3abc+4ab2﹣a2b}+3ab2=5abc﹣2a2b+3abc﹣4ab2+a2b+3ab2=8abc﹣a2b﹣ab2;
将a,b,c的值代入得:原式=
(3)根据题意得,(x﹣2)2+|xy﹣4|=0则,(x﹣2)2=0,|xy﹣4|=0解得:x=2,y=2
原式=3x2y+{﹣2x2y﹣[﹣2xy+(x2y﹣4x2)﹣xy]+xy2}=3x2y+{﹣2x2y﹣[﹣2xy+x2y﹣4x2﹣xy]+xy2}=3x2y+{﹣2x2y+2xy﹣x2y+4x2+xy+xy2}=3x2y﹣2x2y+2xy﹣x2y+4x2+xy+xy2=4x2+3xy+xy2
将x=2,y=2代入得:原式=36

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