下列关于数列的命题
① 若数列

是等差数列,且

(

为正整数)则
② 若数列

是公比为2的等比数列
③ 2和8的等比中项为±4
④ 已知等差数列

的通项公式为

,则

是关于

的一次

函数
其中真命题的个数为 ( )
练习册系列答案
相关习题
科目:高中数学
来源:不详
题型:填空题
已知

是数列{

}的前n项和,并且

=1,对任意正整数n,

;设

).(I)证明数列

是等比数列,并求

的通项公式;
(II)设

的前n项和,求

.
查看答案和解析>>
科目:高中数学
来源:不详
题型:填空题
已知数列

为等差数列,且

,

,则

___

_________.
查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
(本题满分14分)
在数列

中,

时,其前

项和

满足:

(1)求

;
(2)令

,求数列

的前

项和

查看答案和解析>>
科目:高中数学
来源:不详
题型:解答题
(本题满分14分)
在数列

中,

时,其前

项和

满足:

(Ⅰ)求

;
(Ⅱ)令

,求数列

的前项和

查看答案和解析>>