已知sn=32n-n^2求等差数列|an|的前n项和sn
已知等差数列前n项和 sn=2n^2+3n求an
已知等差数列{an}的前n项和为Sn,且(2n-1)Sn+1 -(2n+1)Sn=4n²-1(n∈N*)
已知等差数列{an}的前n项和Sn=n²求an
已知等差数列{an}的前n项和为Sn,且a1不等于0,求(n*an)/Sn的极限、(Sn+Sn+1)/(Sn+Sn-1)
已知等差数列{an}的前n项和为Sn,如果Sn=(an+1/2)^2(n∈N+0,bn=(-1)^n*Sn
{an}是等差数列前n项和Sn已知Sm=a Sn-Sn-m=b 求Sn
等差数列{an}前n项和为Sn=3n-2n^2,求an
等差数列{An}的前n项和为Sn,若 lim Sn/n方 =2
已知等差数列{an}的前n项和Sn=25n-2n方,求数列{|an|}的前n项和Tn
已知数列{an}的前n项和为Sn=1+2+3+4+…+n,求f(n)= Sn /(n+32)Sn+1的最大值
设Sn是等差数列an的前n项和,a5=2,an-4=30(n≥5,n∈N*),Sn=136,求n
已知等差数列{an}前n项和Sn=-2n^2-n