首页
在数列{an}中,已知a1=-1,an+1=2an-n+1,(n=1,2,3,…).(1)...
试题详情
在数列{a
n}中,已知a
1=-1,a
n+1=2a
n-n+1,(n=1,2,3,…).
(1)证明数列{a
n-n}是等比数列;
(2)
![](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAFQAAAAxCAYAAABEUo4oAAAAAXNSR0IArs4c6QAAAARnQU1BAACx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)
为数列{b
n}的前n项和,求S
n的表达式.
相关试题
-
在数列{an}中,已知a1=-1,an+1=2an-n+1,(n=1,2,3,…).
(1)证明数列{an-n}是等比数列;
(2)
为数列{bn}的前n项和,求Sn的表达式.
-
在数列{an}中,已知a1=-1,an+1=2an-n+1,(n=1,2,3,…).
(1)证明数列{an-n}是等比数列;
(2)
为数列{bn}的前n项和,求Sn的表达式.
-
已知数列{an}满足a1=2,an+1=2an-n+1(n∈N+).
(1)证明数列{an-n}是等比数列,并求出数列{an}的通项公式;
(2)数列{bn}满足:
(n∈N+),求数列{bn}的前n项和Sn;
(3)比较Sn与
的大小.
-
在数列{an}中,a1=2,an+1=2an-n+1,n∈N*.
(1)证明数列{an-n}是等比数列;
(2)设Sn是数列{an}的前n项和,求使2Sn>Sn+1的最小n值.
-
已知数列{an}的前n项和为Sn,且满足Sn=2an-n,(n∈N*)
(Ⅰ)求a1,a2,a3的值;
(Ⅱ)证明{an+1}是等比数列,并求an;
(Ⅲ)若bn=(2n+1)an+2n+1,数列{bn}的前n项和为Tn.
-
已知数列an=
,记Sn=a1+a2+a3+…+an,用数学归纳法证明Sn=(n+1)an-n.
-
已知数列{an}是等比数列,Sn为其前n项和.
(1)若S4,S10,S7成等差数列,证明a1,a7,a4也成等差数列;
(2)设
,
,bn=λan-n2,若数列{bn}是单调递减数列,求实数λ的取值范围.
-
已知数列{an}是等比数列,Sn为其前n项和.
(1)若S4,S10,S7成等差数列,证明a1,a7,a4也成等差数列;
(2)设
,
,bn=λan-n2,若数列{bn}是单调递减数列,求实数λ的取值范围.
-
已知数列{an}是等比数列,Sn为其前n项和.
(1)若S4,S10,S7成等差数列,证明a1,a7,a4也成等差数列;
(2)设
,
,bn=λan-n2,若数列{bn}是单调递减数列,求实数λ的取值范围.
-
在数列{an}中,已知a1=2,an+1=4an-3n+1,n∈N*.
(1)设bn=an-n,求数列{bn}的通项公式;
(2)设数列an的前n项和为Sn,证明:对任意的n∈N*,不等式Sn+1≤4Sn恒成立.