设等差数列{an}的公差为d,则"a1,a2,a3,a4,a5,a6,a7的方差为1"的充要不得条件是d=

设等差数列{an}的公差为d=1,且a3+a5=8,则a1+a9= 设等差数列｛an｝的公差为d不为0,a1＝9d,若ak是a1与a2k的等比中项,则k＝ 若等差数列a1,a2,a3,...,an,...的公差为d,则数列a1,a4,a7,...,a3n-2,...公差为 11、设等差数列{an}的公差d≠0,a1=4d,若ak是a1与a6的等比中项,则k的值为 7、设等差数列{an}的公差d≠0,a1=4d,若ak是a1与a6的等比中项,则k的值为 设等差数列{an}公差d≠0 a1=4d,若ak是a1与a2k的等比中项,则k的值为 设等差数列{An}的公差d不为0,A1=9d.若Ak是A1与A2k的等比中项,则k等于几 设等差数列{an}的公差d不为0,a1=9d,若ak是a1与a2k的等比中项,则k=? 设等差数列{an}的公差d不为0,a1=9d.若ak是a1与a2k的等比中项,则k=? 设等差数列an的公差d不为0,a1=9d.若ak是a1与a2k的等比中项,则k等于多少? 设等差数列{an}公差d不为0,a1=9d,若ak是a1和a2k的等比中项,则k=______ 等差数列{an}的公差为d,且a1,a2,a5成等比数列,则d=? 设数列{an}的前n项和为Sn,若{an}和{根号sn+n}都是公差为d的等差数列,则a1= 设公差为d的等差数列{an}的前n项和为Sn,若a1=1,-2/17 设等差数列{an}的公差为d,则a1,a2,a3,a4,a5,a6,a7的方差为1的充要不得条件是d= 设等差数列an公差为d,则a1 a2 a3 a4 a5 a6 a7 的方差为1 的充要条件是d=? 设等差数列{an}公差为d,若a1,a2,a3,a4,a5,a6,a7的方差为1,则d=?需要详细过程,谢谢好心人! 等差数列{an}的公差为d,则数列a1+a4,a2+a5,a3+a6,.是什么数列