文档介绍：Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 图象性质 a>1 (1) 定义域:(2) 值域:(3) 过定点:(4) 单调性: (5) 奇偶性: 0<a<1 (4) 单调性: (5) 奇偶性: R (0,+ ∞) (0,1) 指数函数的图象和性质增函数减函数非奇非偶非奇非偶(6) 当x>0 时, y>1 .当x<0 时, 0<y<1 . (6) 当x>o 时, 0<y<1 , 当 x<0 时, y>1 . x yo 1x yo 1复习: Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 例1 比较下列各题中两数值的大小① , 3.② - , - ②因为指数函数 y= x在R 上是减函数. - >- ∴ - < - 解: ①因为指数函数 y= x在R 上是增函数. <3 所以 < 3 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 练习 1:比较大小?① - ?② ?③ b 2 b 4 (0<b<1) 归纳:比较两个底数相同指数不同幂的大小时,可以构造一个指数函数,再利用指数函数的单调性即可比较大小. 当a >1 ,幂越大则越大(即 X越大则越大) 当0 < a <1 ,幂越大则越小(即 X越大则越小) ><> ④ a (a>0 且a≠1) Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 10 8 6 4 2 -5 5 sx?? x rx?? x qx?? x hx?? x gx?? x fx?? x Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 例2、比较下列各题中两数值的大小① ( ) ,1 ② - , - :比较两个不同底数幂的大小时,: ①∵( ) >( ) 0 =1 ∴( ) >1 ②∵ - > 0 =1 - 0