等差数列{an}的前n项和为Sn,若S2=2,S4=10,则S6等于( )
已知等差数列{an}的前n项和为Sn,若S4=6,S6=4,求S10
已知等比数列{an}的前n项和为Sn(an∈R),且S2=7,S6=91,则S4的值为( )
设等差数列{an}的前n项和为Sn,若S2=4,S4=20,则该数列的公差d等于多少?
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=______.
设等差数列{an}的前n项和为Sn,若a1=3,S6-S2=27.
设Sn是等差数列An的前n项和,若S3/S6=1/3,则S6/S12等于
等比数列an的公比为1/3,前n项和为Sn,n属于正整数.如S2,S4-S2,S6-S4成等比数列.则其公比为
设等比数列{an}的公比q=2,前n项和为Sn,则S4/S2等于
设等差数列{An}的前n项和为Sn,S4=4S2,A2n=2An+1 ,(1)求数列{an}的通
设等差数列前n项和为Sn,若a1=0.5,S4=20,则S6为
设等差数列an的前n项和为Sn,若S4>=10,S5
设数列{an}为等差数列,其前n项和为Sn,且S4=-62,S6=-75