4绝对值与相反数.pdf

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1、1/4 课题2.3 绝对值与相反数课时31 授课时间班级课型新授授课人教案目标1.理解有理数的绝对值概念，并掌握其表示方法；2.熟练掌握求一个有理数的绝对值的方法；3.渗透数形结合等思想方法，培养学生的概括能力教学重、难点重点：理解有理数的绝对值概念，并掌握其表示方法；难点：熟练掌握求一个有理数的绝对值的方法。教、学具投影片，小黑板预习要求1.阅读课本 P23 24；2.完成课本 P24 的例题。教 师 活 动 内 容、方 式学生活动方式、内容旁注一、创设情境：1.让学生画一条数轴，并在数轴上标出下列各数：在讨论数轴上的点与原点的距离时，只需要观察它与原点之间相隔多少个单位长度，与位于原点何方

2、无关2.两辆汽车，第一辆沿公路向东行驶了5 千M，第二辆向西行驶了4 千 M为了表示行驶的方向(规定向东为正)和所在位置，分别记作+5千M 和-4 千 M这样，利用有理数就可以明确表示每辆汽车在公路上的位置了我们知道，出租汽车是计程收费的，这时我们只需要考虑汽车行驶的距离，不需要考虑方向当不考虑方向时，两辆汽车行驶的距离就可以记为 5 千 M 和 4 千 M揭示生活中确实存在只需考虑距离的问题这里的5 叫做+5 的绝对值，4 叫做-4 的绝对值教 师 活 动 内 容、方 式学生活动方式、内容旁注2/4 二、新知讲解：我们把在数轴上表示a 的点与原点的距离叫做 数a 的 绝 对 值（absolu

3、te value），记 作|a|例如，在数轴上表示数-6 的点和表示数6的点与原点的距离都是6，所以，-6 和 6 的绝对值都是 6，记作|-6|6|6 口答：（1）|+6|，|0.2|，|+8.2|；（2）|0|；（3）|-3|，|-0.2|，|-8.2|.由绝对值的意义，结合上面口答结果，引导学生归纳出：1一个正数的绝对值是它本身；2零的绝对值是零；3一个负数的绝对值是它的相反数由此可以看出，不论有理数a 取何值，它的绝对值总是正数或0（通常也称非负数）即对任意有理数a，总有这是一条重要的性质三、实践应用例 1 求下列各数的绝对值：让学生口述文档编码:CA8S5F5Q6Z4 HM10N6T

4、3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4

5、K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S

6、5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N

7、6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7

8、W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA

9、8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM1

10、0N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M33/4 教 师 活 动 内 容、方 式学生活动方式、内容旁注例2化简：四、交流反思和学生一起归纳本节课主要内容：1.一个正数的绝对值是它的本身；一个负数的绝对值是它的相反数；零的绝对值是零2.从数轴看，一个数a 的绝对值就是数轴上表示数 a 的点到原点的距离3.要注意一个数的绝对值不可能是负数五、巩固练习1.课

11、本 P24 练习2.求下列各数的绝对值：-5，4.5，-0.5，+1，03.填空：（1）-3 的符号是 _,绝对值是 _。（2）符号是“+”号，绝对值是7 的数是 _。（3）10.5 的符号是 _,绝对值是 _。（4）绝对值是5.1，符号是“-”号的数是 _六、布置作业课本 P28 习题 1.本课教育评注（课堂设计理念，实际教案效果及改进设想）文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码

12、:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4

13、HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5

14、ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档

15、编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z

16、4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G

17、5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3

18、文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M34/4 文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S

19、5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N

20、6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7

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22、8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM1

23、0N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3文档编码:CA8S5F5Q6Z4 HM10N6T3B5G5 ZV4X7W4K9M3