题目内容
计算:5x(x2-2x+4)+x2(x-1)
解: 5x(x2-2x+4)+x2(x-1)
=(5×1)·x·x2-(5×2)·x·x+(5×4)·x+x2·x-(1×1)x2
=5x3-10x2+20x+x3-x2
=6x3-11x2+20x
=(5×1)·x·x2-(5×2)·x·x+(5×4)·x+x2·x-(1×1)x2
=5x3-10x2+20x+x3-x2
=6x3-11x2+20x
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