若等差数列an的公差d
若等差数列an的公差d
等差数列an的公差d
等差数列{an}的公差d
已知等差数列{An}的公差d
关于等差数列的一道题等差数列{an}的公差d
等差数列{an}中,公差d
已知等差数列an的公差d不等于0
在等差数列{an}中,若|a3|=|a9|,公差d
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
等差数列an的公差为d=2,若a1,a3,a4成等比数列,求a2.
已知等差数列[an]的公差d不等于零,若a5,a9,a15成等比数列,公比为?
记数列{an}的前n项和为Sn,若{Sn/an}是公差为d的等差数列,则{an}为等差数列的充要条件是d=?