化简 (1)2x2y﹣2xy﹣4xy2+xy+4x2y﹣3xy2(2)3 (4x2﹣3x+2)﹣2 (1﹣4x2+x) (3)5abc﹣2a2b﹣[3abc﹣3
题型:解答题难度:一般来源:期中题
化简 (1)2x2y﹣2xy﹣4xy2+xy+4x2y﹣3xy2 (2)3 (4x2﹣3x+2)﹣2 (1﹣4x2+x) (3)5abc﹣2a2b﹣[3abc﹣3 (4ab2+a2b)] (4)(2x2+x)﹣2[x2﹣2(3x2﹣x)]. |
答案
解:(1)2x2y﹣2xy﹣4xy2+xy+4x2y﹣3xy2=2x2y+4x2y﹣2xy+xy﹣4xy2﹣3xy2=6x2y﹣xy﹣7xy2; (2)3 (4x2﹣3x+2)﹣2 (1﹣4x2+x)=12x2﹣9x+6﹣2+8x2﹣2x=20x2﹣11x+4 (3)5abc﹣2a2b﹣[3abc﹣3 (4ab2+a2b)]=5abc﹣2a2b﹣[3abc﹣12ab2﹣3a2b]=5abc﹣2a2b﹣3abc+12ab2+3a2b=2abc+a2b+12ab2; (4)(2x2+x)﹣2[x2﹣2(3x2﹣x)]=2x2+x﹣2[x2﹣6x2+2x]=2x2+x﹣2x2+12x2﹣4x=12x2﹣3x; |
举一反三
先化简,再求值:已知A=3x2y﹣xy2,B=﹣xy2+3x2y,求5A﹣4B的值,其中x=﹣2,y=﹣3. |
已知﹣2xmy与3x3yn是同类项,求m﹣(m2n+3m﹣4n)+(2nm2﹣3n)的值. |
下列计算正确的是 |
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A.x2y﹣2xy2=﹣x2y B.2a+3b=5ab C.﹣3ab﹣3ab=﹣6ab D.a3+a2=a5 |
若关于a,b的多项式3(a2﹣2ab﹣b2)﹣(a2+mab+2b2)中不含有ab项,则m=( ). |
化简:,其中x=2,y=. |
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