Sn=1/8*(an+2)^2
Sn+1=1/8*(an+1+2)^2
Sn+1-Sn=1/8*[(an+1^2+4an+1)-(an^2+4an)]
8an+1=(an+1^2+4an+1)-(an^2+4an)
(an+1^2-4an+1+4)-(an^2+4an+4)=0
(an+1-2)^2-(an+2)^2=0
(an+1-2)^2=(an+2)^2
an+1-2=an+2或an+1-2=-an-2
an+1-an=4或an+1+an=0
求此数列题详细解法已知数列an Sn=1/8(an+2)^2 求证an是等差数列
1个回答
相关问题
-
已知数列{An},Sn=0.125（An+2)(An+2).求证：{An}是等差数列
-
已知数列{an}中,已知a1=1,an+1=an/1+2an,(1)求证数列{1/an}是等差数列；（2）求数列｛an｝
-
①已知数列{an}满足a1=1,an+1=an/3an+1,求证数列{1/an}是等差数列②sn=1+x²+.
-
数列题一道,已知数列an中,a1=3,前n项和为Sn=1/2(n+1)(an+1)-1.(1)求证:数列an是等差数列
-
在数列{an}中,an=SnS（n-1）(n≥2),且a1=2/9 求证数列{1/Sn)是等差数列,求
-
已知数列{an}满足a1=1,an+1=2an+1.(1)求证:数列{an+1}是等比数列;(2)求an和Sn的表达式.
-
已知各项不为0的数列an 前n项和为sn sn=n(1+an)/2 求证数列an为等差数列
-
已知数列{an}满足a1=2,a(n+1)=(3an-2)/(2an-1),求证{1/(an-1)}是等差数列,并求数列
-
（1）已知数列｛an｝是等差数列,求证数列｛e^an｝是等比数列.
-
已知数列{an}满足:a1=3,an=Sn-1+2n,求数列an及sn