等差数列｛an｝s90=10,d=2,求a3+a6+a9+.a90

等差数列｛an｝s90=10,d=2,求a3+a6+a9+.a90 已知等差数列{an}的公差d>0,其前n项和为sn,满足S90,则n=多少时,sn最小 等差数列{an}的公差d>0,其前n项和为Sn,满足S90,则n=____时,Sn最小. 求证等差数列已知{an}为等差数列,公差d=3,求证：{2*an+3}是等差数列并求公差d 等差数列{an}中,d=2,n=5,an=-10,求a1及Sn 1.等差数列{an}.a6+a35=10 ,求S402.已知等差数列{an}中,a1=5/6,Sn=-5 ,an=-3/2 求n和d 等差数列d=2,n=15,an=-10求a1和Sn 等差数列d=2,n=15,an=-10求a1和Sn 在等差数列｛an｝中,已知d=2,n=15,an=-10,求a1及Sn 在等差数列｛an｝中,已知d=2,n=15,an=-10,求a1及Sn 已知等差数列{An}中,A1=3,An=21,d=2,求n 等差数列AN中D=2 ,AN=11,SN=35 求A1与N? 在等差数列中,已知d=2,an=1,sn=8求an,n 已知等差数列{an},满足d>0,an*a(n+1)=4n^2-1,求等差数列an的通项公式 一道等差数列题目在等差数列｛an｝中,a5=0,a10=10求a1与等差d 已知an为公差d不等于0的等差数列,且an/n的极限=2,求d {an}是等差数列,Sn=n2-2n,求：an 已知等差数列an中a10=10 s10=70 求d=? 在等差数列{an}中,a5 = 0,a10 = 10,求a1与公差d.