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,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,数列,数列,数列,数列,6.2.1,等差数,列的定义,6.2,等差数列,创设情境 兴趣导入,将正整数中,5,的倍数从小到大列出,组成数列:,5,,,10,,,15,,,20,,, (,1,),将正奇数从小到大列出,组成数列:,1,,,3,,,5,,,7,,,9,,, (,2,),观察数列中相邻两项之间的关系,,从第,2,项开始,数列,(1),中的每一项与它前一项的差都是,5,从第,2,项开始,数列(,2,)中的每一项与它前一项的差都是,2,动脑思考 探索新知,如果一个数列从第,2,项开始,每一项与它前一项的,差都等于同一个常数,那么,这个数列叫做,等差数列,这个常数叫做等差数列的,公差,,一般用字母,d,表示,(,6.1,),为等差数列,,d,为公差,则,若数列,即,6.2,等差数列,练习一,抢答:下列数列是否为等差数列?,1,,,2,,,4,,,6,,,8,,,10,,,12,,, ,0,,,1,,,2,,,3,,,4,,,5,,,6,,, ,3,,,3,,,3,,,3,,,3,,,3,,,3,,, ,2,,,4,,,7,,,11,,,16,,, ,8,,,6,,,4,,,-2,,,0,,,2,,,4,,, ,3,,,0,,,3,,,6,,,9,,, ,练习二,说出下列等差数列的公差,0,,,1,,,2,,,3,,,4,,,5,,,6,,, (1),3,,,3,,,3,,,3,,,3,,,3,,,3,,, (2),-8,,,-6,,,-4,,,-2,,,0,,,2,,,4,,, (3),3,,,0,,,-3,,,-6,,,-9,,, (4),d,= 1,d,= 0,d,= 2,d,=,-,3,常数列,巩固知识 典型例题,例,已知等差数列的首项为,12,,公差为,5,,,试写出这个数列的第,2,项到第,5,项,解,由于,因此,6.2,等差数列,运用知识 强化练习,这个数列的第,8,项,2,.,写出等差数列,11,,,8,,,5,,,2,,,的第,10,项,6.2,等差数列,公差,试写出,为等差数列,已知,1,.,作业布置,第六页 第,1,题、第,2,题,
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