等差数列an的前n项和为sn,若a2+a3=4,则s4=
等比数列{an}的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1=1,则S4=( )
设等差数列{an}的前n项和为Sn,若a5=5a3,则S4/S5
等比数列an的前n项和为Sn,且4a1,2a2,a3成等差数列.若a1等于1,则S4为多少?
等比数列{an}的前n项和为Sn,且4a1,2a3,a3成等差数列,若a1=1,则S4=?
等比数列{an}的前n项的和为Sn.若4a1.2a2.a3成等差数列,则S4/a4的值是?
在公比不为1的等比数列{an}中,前n项的和为Sn,若S2,S4,S3成等差数列,则a2,a4,a3成等差数列.
已知等差数列{an}的前n项和为Sn,a3=0,S4=-4.
数学必修五的题1等差数列{an}的前N顶和为Sn,若a2=1,a3=3,则s4=2等差数列{an}中,a5+a13=40
记等差数列{an}的前n项和为Sn,已知a2+a4=6,S4=10.
记等差数列{an}的前n项和为Sn,已知a2+a4=6,S4=10.
设等差数列an的前n项和为Sn,若S4>=10,S5
已知sn是公差不为0的等差数列{an}的前n项和,且s1,s2,s4成等比数列,则a1分之a2+a3