六年级数学上册《整数乘法运算定律推广到分数乘法》PPT课件(人教新课标).ppt

* * * * * * 人教新课标六年级数学上册课件 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 它们相等吗？ ①25 × 36 36 × 25 ②（17 × 25） × 4 17 × （25× 4） ③ 72 × 13+28 × 13 （72+28） × 13 乘法交换律 乘法结合律 乘法分配律 = = = Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 回顾： 乘法交 换 律： a×b = b × a 乘法结 合 律： a×b ×c = a×( b × c) 乘法分配 律： (a+b )×c = a C +b c Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 下面每组算式的左右两边有什么关系？ 整数乘法的交换律、结合律和分配律，对于分数乘法也适用 = = = Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 这道题如何计算比较简便?应用了什么定律？ 算一算： Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 这道题如何计算比较简便?应用了什么定律？ 算一算： Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 小结 1、 分数混合运算的顺序和整数的运算顺序相同。 2、整数乘法的运算定律同样适合分数乘法，但在计算时一定要认真观察已知数有什么特点应用什么运算定律可以使计算简便。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 能力提高（一） Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 怎么改,用乘法分配 律做就比较简便? Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.