证明:数列{an}为等差数列的充要条件是{an}前n项和Sn=An^2+Bn
证明:数列{an}为等差数列的充要条件是数列{an}的前n项和为sn=an²+bn(其中啊a,b为常数)
试证明:数列{an}为等差数列的充要条件是其前n项和Sn=an^2+bn(常数a,b∈R) 感激.
数列an的前n项和为Sn=an*2+bn+c,则数列an是等差数列的充要条件是
已知数列的前n项和Sn=An∧2+Bn+C,求{an}成等差数列的充要条件
a1=1.an+1=2an+2^n.bn=an/2^n-1.证明bn是等差数列、求数列的前n项和sn?
已知数列{An}的前n项和为Sn=(n+1)2+t,证明:{An}成等差数列的充要条件是t=-1
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
已知数列an满足a1=2 其前n项和为Sn Sn =n+7~3an 数列bn满足 bn=an~1 证明数列bn是等差数列
数列an的前n项和为Sn,Sn=4an-3,①证明an是等比数列②数列bn满足b1=2,bn+1=an+bn.求数列bn
若数列An的前n项和为Sn=an^2+bn+c,(a,b,c属于正整数)则An为等差数列的充要条件是c=0.
数列(an)的前n项和Sn=an的2次方+bn,试证明数列是等差数列,并求a1和d
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