已知在数列an中,Sn=2n^2+3n,求证an是等差数列
已知在数列an中,Sn=2n^2+3n,求证an是等差数列
已知数列{an}的前n项和为Sn=n^2-3n,求证:数列{an}是等差数列
已知数列an其前n项和为Sn,且Sn=3n^2+5n,求证数列an是等差数列
已知数列{an}的前n项和sn满足sn=an^2+bn,求证{an}是等差数列
高一数学问题:已知数列{An}的前n项和为Sn=n^2+3n,求证:数列{An}是等差数列.
已知数列{an}的前n项和sn=n方+3n,求证数列{an}是等差数列
已知数列an中,a1=1,当n大于等于2时,sn=an(1-2/sn).求证1/sn是等差数列
在等差数列an 的前n项和为Sn=2n^2+3n+2 求通项公式?,求证数列{an}从第二项开始是等差数列
已知数列{an}中,a2=2,前n项和为Sn,且Sn=n(an+1)/2证明数列{an+1-an}是等差数列
在数列{An}中,已知A1=1,An=2Sn^2/(2Sn-1),(n>=2),证明{1/Sn}是等差数列,并求Sn
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
已知数列{an}前n项和为sn=3n^2-n,求证其为等差数列