摘要:设数列{an}的首项a1=1.前n项和Sn满足关系式:3tSn-(2t+3)Sn-1=3t(t>0,n=2,3,4-). (1)求证:数列{an}是等比数列, (2)设数列{an}的公比为f(t).作数列{bn}.使b1=1,bn=f()(n=2,3,4-).求数列{bn}的通项bn, (3)求和:b1b2-b2b3+b3b4--+b2n-1b2n-b2nb2n+1.
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设数列{an}的首项a1=1,前n项和Sn满足关系式tSn-(t+1)Sn-1=t(t>0,n∈N*,n≥2).
(Ⅰ)求证:数列{an}是等比数列;
(Ⅱ)设数列{an}的公比为f(t),作数列{bn},使b1=1,bn=f(
)(n∈N*,n≥2),求数列{bn}的通项公式;
(Ⅲ)数列{bn}满足条件(Ⅱ),求和:b1b2-b2b3+b3b4-…+b2n-1b2n-b2nb2n+1. 查看习题详情和答案>>
(Ⅰ)求证:数列{an}是等比数列;
(Ⅱ)设数列{an}的公比为f(t),作数列{bn},使b1=1,bn=f(
| 1 | bn-1 |
(Ⅲ)数列{bn}满足条件(Ⅱ),求和:b1b2-b2b3+b3b4-…+b2n-1b2n-b2nb2n+1. 查看习题详情和答案>>
设数列{an}的首项a1=1,前n项和Sn满足关系式.3tSn-(2t+3)Sn-1=3t(其中t>0,n=2,3,4,…)
(1)求证:数列{an}是等比数列..(2)设数列{an}的公比为f(t),作数列{bn},使b1=1,bn=f(
)(n=2,3,4…)求数列{bn}的通项公式.(3)求和Sn=b1b2-b2b3+b3b4 -…+(-1)n-1bnbn+1.
查看习题详情和答案>>
(1)求证:数列{an}是等比数列..(2)设数列{an}的公比为f(t),作数列{bn},使b1=1,bn=f(
| 1 | bn-1 |
设数列{an}的首项a1=1,前n项和Sn满足关系式:3tSn-(2t+3)Sn-1=3t(t>0,n=2,3,4,…)
(1)求证:数列{an}是等比数列;
(2)设数列{an}是公比为f(t),作数列{bn},使b1=1,bn=f(
)(n=2,3,4,…),求和:b1b2-b2b3+b3b4-…+b2n-1b2n-b2nb2n+1;
(3)若t=-3,设cn=log3a2+log3a3+log3a4+…+log3an+1,Tn=
+
+…+
,求使k
≥(7-2n)Tn(n∈N+)恒成立的实数k的范围.
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(1)求证:数列{an}是等比数列;
(2)设数列{an}是公比为f(t),作数列{bn},使b1=1,bn=f(
| 1 |
| bn-1 |
(3)若t=-3,设cn=log3a2+log3a3+log3a4+…+log3an+1,Tn=
| 1 |
| c1 |
| 1 |
| c2 |
| 1 |
| cn |
| n•2n+1 |
| (n+1) |