求Sn
an是等差数列,求lim (Sn+Sn+1)/(Sn+Sn-1)
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)
{an}是等差数列前n项和Sn已知Sm=a Sn-Sn-m=b 求Sn
已知数列an是等差数列,且a1不等于0,Sn为这个数列的前n项和,求limnan/Sn.limSn+Sn-1/Sn+Sn
求Sn=a+aa+aaa+aaaa+.
数列an=n2,求Sn
求到这里 Sn怎么表达!
1+2+3+4+.+n,求Sn
数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn
正项无穷等比数列{an}前n项和为Sn,lim(Sn/Sn+1)=1 求公比范围
已知数列an,an>0,Sn=a1+a2+a3.+an,且an=6Sn/an + 3,求Sn!
已知数列 an前n项和为Sn,a1=1,Sn=2a(n+1),求Sn