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15.2.3整数指数幂(一) Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 正整数指数幂有哪些运算性质 ? ( 1) aman=am+n (a0 m、 n为正整数 ) ( 2) (am)n=amn (a0 m、 n为正整数 ) ( 3) (ab)n=anbn (a, b0 m、 n为正整数 ) ( 4) am an=am-n (a0 m、 n为正整数且 mn) ( 5) ( b0 , n是正整数) n n n b a b a )( 当 a0时, a0=1。( 0指数幂的运算) ( 6) Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. am an=am-n (a0 m、 n为整数 ) a5 a3=a2 a3 a5=? 分 析 a3 a5=a3-5=a-2 a3 a5= 5 3 a a = 23 3 aa a 2 1 a 2 12 a a Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. n是正整数时 , a-n属于分式。并且 nana 1 (a0) 例如 : aa 11 5 15 aa 引入负整数指数幂后,指数的取值范围就扩大到全体整数。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. )0( 1 a a a n n 这就是说: a n( a0) 是 an 的倒数 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. ( 1) 32=_, 30=_, 3-2=_; ( 2) (-3)2=_, (-3)0=_, (-3)-2=_; ( 3) b2=_, b0=_, b-2=_(b0). 练 习 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. a3 a-5 = a-3 a-5 = a0 a-5 = a-2 a-8 a-5 am an=am+n,这条性质对 于 m, n是任意整数的情形 仍然适用。 归 纳 2 1 a 8 1 a 5 1 a Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 整数指数幂有以下运算性质: ( 1) aman=am+n (a0) ( 2) (am)n=amn (a0) ( 3) (ab)n=anbn (a,b0) ( 4) am an=am-n (a0) ( 5) ( b0) n n n b a b a )( 当 a0时, a0=1。 ( 6) a-3a-9= (a-3)2= (ab)-3= a-3 a-5= 2)( b a Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 例题: (1)(a-1b2)3; (2) a-2b2 (a2b-2)-3 跟踪练习: (1) x2y-3(x-1y)3; (2) (2ab2c-3)-2 (a-2b)3 2 2 3 )(3( a b 23 )()(3( xy y x Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 课堂达标测试 基础题: 1.计算: (1)(a+b)m+1(a+b)n-1; (2) (-a2b)2(-a2b3)3 (-ab4)5 (3) (x3)2 (x2)4x0 (4) (-1.8x4y2z3) (-0.2x2y4z) (-1/3xyz) 提高题: 2.已知 , 求 a51 a8的值; 0)1(2 2 bab Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 3.计算: xn+2xn-2 (x2)3n-3; 4.已知: 10m=5,10n=4,求 102m-3n. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 小 结 n是正整数时 , a-n属于分式。并且 nana 1 (a0) Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.
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