已知等差数列(an)中,公差d>0,其前n项和为Sn,且.
已知等差数列(an)中,公差d>0,其前n项和为Sn,且.
已知等差数列{an}中,公差d>0,其前n项和为Sn,且满足a2·a3=45,a1+a4=14
已知等差数列{an}中,公差d>0,其前n项和为sn,且满足a2a3=45,a1+a4=14
已知等差数列{an}中,公差d>0,其前n项和为Sn,且满足a2×a3=45,a1+a4=14
等差数列{an}中,公差为d,已知a4=84,前n项和为Sn,且S10>0,S11
已知等差数列{an}中,公差d>0,其前n项和为Sn,且满足:a2*a3=45,a1+a4=14
已知等差数列{an}中,公差d>0,其前n项和为Sn,且满足a2*a4=45,a1+a5=14
已知等差数列{An}中,公差d大于0,其前n项和为Sn,且满足:a2a3=45,a1+a4=14.
数列an是公差d不等于0的等差数列,其前n项和为Sn,且
已知等差数列{an}中,公差d>0,前n项和为Sn,且满足a2*a3=45,a1+a5=18
已知等差数列{an}的公差d不等于0,其前n项和为sn,且a1,a3,a9成等比数列,则s3/s7=多少
已知等差数列{an}公差为d(d≠0),前n项和为Sn,Xn表示{an}前n项的平均数,且数列{Xn}补充如下: