设{an}是等差数列,求证以b=(a1+a2+a3+...+an)/n为通项公式的数列{bn}是等差数列

设{an}是等差数列,求证以b=(a1+a2+a3+...+an)/n为通项公式的数列{bn}是等差数列 等差数列求和 难题设｛An}是等差数列,求证：以bn=a1+a2+...an/n (n属于N+）为通项公式的数列｛bn}是等差数列 设an是等差数列,求证以bn=(a1+a2+a3+…+an)/n,n属于N+为通项公式的数列bn是等差数列 一道求证等差数列题目,a1=1 ,an=2a(n-1)+ 2^(n-1) 设bn= an/2^(n-1) 求证bn是等差数列 求证等差数列,a1=1 ,an=2a(n-1)+ 2^(n-1) 设bn= an/2^(n-1) 求证bn是等差数列 以知数列{An}是等差数列,{Sn}是其前n项的和,求证：S6,S12-S6,S18-S12 成等差数列.设K∈N* Sk,S2k-Sk,S3k-S2k 成等差数列吗.A= S6=6*(a1+a6)/2=3(a1+a6) B= S12-S6=6*(a1+a12)/2-6*(a1+a6)/2=3（a12-a6） C= S18-S12=6*(a1+a18)/2-6*(a 设数列an,bn满足:bn=(a1+a2+a3+a4+...+an)/n,若bn是等差数列,求证an也是等差数列 设数列an是等差数列,a1 设数列an是等差数列,a1 设数列{an}为等差数列,求证bn=（a1+a2+...+an）/n（n属于正整数）为通项公式的数列｛bn｝是等差数列 设数列{bn}为等差数列,求证bn=（a1+a2+...+an）/n（n属于正整数）为通项公式的数列｛an｝是等差数列 设{an}是等差数列,且首项a1>0,公差d>0求证:1/a1a2+1/a2a3+…+1/anan+1=n/a1(a1+nd) 数列求证题设等差数列{An}的公差为d,d>0,数列{B}是公比为q等比数列,且B1=A1>0.若A2=B2,求证：当n>2时,An 在以d为公差的等差数列an中,设S1=a1+a2.+an,S2=an+1+an+2+a2n,S3=a2n+1+a2n+a3n,求证S1,S2,S3,也是等差数列,并求其公差 已知正项数列{an},{bn}满足：对任何正整数n,都有an,bn,a(n+1）成等差数列,bn,a(n+1),b(n+1)成等比数列,且a1=10,a2=15求证：数列(根号Bn)是等差数列求数列{an},{bn}通用公式设Sn=1/(a1)+1/(a2)+1/(a3)+.1/(an)如果 设数列{an}的前几项和为Sn,a1=10 an+1=9Sn+10 求证{lgan}是等差数列半小时内解决 ①设an是等差数列,求证：{Sn/n}是等差数列②在等差数列an中,a1=-2010,其前n项和为Sn,若S2009/2009-S2007/2007= 等差数列an中 a8=16 a1+a2+a3=12 求证{an +2 }为等差数列这样写行不行设an+2=bnbn-b(n-1)=an+2-(a(n-1)+2)=an-a(n-1)∵等差数列an∴bn=an+2为等差数列.这么着行不行.