化简:(1)﹣3x2y+2x2y+3xy2﹣2xy2;(2)3(a2﹣2ab)﹣2(﹣3ab+b2);(3)5abc﹣{2a2b﹣[3abc﹣(4a2b﹣ab2
题型:解答题难度:一般来源:江苏期中题
化简: (1)﹣3x2y+2x2y+3xy2﹣2xy2; (2)3(a2﹣2ab)﹣2(﹣3ab+b2); (3)5abc﹣{2a2b﹣[3abc﹣(4a2b﹣ab2]}. |
答案
解:(1)原式=(﹣3+2)x2y+(3﹣2)xy2 =﹣x2y+xy2; (2)原式=3a2﹣6ab+6ab﹣2b2 =3a2﹣2b2; (3)原式=5abc﹣[2a2b﹣(3abc﹣4a2b+ab2)] =5abc﹣(2a2b﹣3abc+4a2b﹣ab2) =5abc﹣2a2b+3abc﹣4a2b+ab2 =8abc﹣6a2b+ab2. |
举一反三
已知:a+b=﹣2,ab=﹣3.求代数式2(4a﹣3b﹣2ab)﹣3(2a﹣b+ab)的值. |
若A=4x2﹣4x+1,B=4x+1,则A﹣B= |
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A.4x2+2 B.4x2 C.4x2﹣8x D.8x2+2 |
下列算式正确的是 |
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A.3a+2b=5ab B.3x5+2x5=5x5 C.6x2y﹣5xy2=x2y D.7ab﹣b=7a |
先化简,再求值 (1)(3x2y﹣xy2)+3(2xy2﹣x2y),其中x=1,y=﹣2; (2)已知:a﹣b=3,ab=﹣1,求(2a+3b﹣2ab)﹣(a+4b+ab)﹣(3ab+2b﹣2a)的值. |
先化简,再求值:2x2y﹣(3xy2﹣4x2y+5xy2),其中x=1,y=﹣1. |
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