设等差数列an的前n项和为Sn,若S4>=10,S5
设等差数列an的前n项和为Sn,若S4>=10,S5
设等差数列{an}的前n项和为Sn,若a5=5a3,则S4/S5
设等差数列{an}的前n项和为Sn,若S4≥10,S5≤15,则a4的最大值为______.
设Sn为等差数列的{an}的前n项和,已知s3,s4的等比中项是S5,s3,s4的等差中项是1,求an?
等差数列{an}的前n项和为Sn,已知S4=S5=-20,若Sn>0则n的最小值为?
设Sn为等差数列{an}的前n项和,若S5=10,S10=—5,
设{an}是公差d≠0的等差数列,Sn是它的前n项和,若a1=4,且S3/3和S4/4的等比中项为S5/5,求{an}的
若Sn是公比为q的等比数列{an}的前n项和,且S4,S6,S5成等差数列,则公比q=______.
等比数列的前n项和为Sn,a1为3/2,且S3,S5,S4成等差数列,求an
设数列(An)是等差数列,且a2=-6,a8=6,Sn是数列(An)的前n项和,求S4,S5,S6.
设等差数列{an}(n∈正整数)的前n项和为Sn,该数列是单调递增数列,若S4≥10,S5≤15,则a4的取值范围
设等差数列[an]的前n项和为Sn,若a5=5a3,则S9/S5等于多少?