已知数列{an}满足3an+1+an=0,a2=-,则{an}的前10项和等于( )
(A)-6(1-3-10) (B)(1-310)
(C)3(1-3-10) (D)3(1+3-10)
设首项为1,公比为的等比数列{an}的前n项和为Sn,则( )
(A)Sn=2an-1 (B)Sn=3an-2
(C)Sn=4-3an (D)Sn=3-2an
已知{an}是递增等比数列,a2=2,a4-a3=4,则此数列的公比q= .
若等比数列{an}满足a2a4=,则a1a5= .
已知等比数列{an}为递增数列.若a1>0,且2(an+an+2)=5an+1,则数列{an}的公比q= .
等比数列{an}中,|a1|=1,a5=-8a2,a5>a2,则an等于( )
(A)(-2)n-1 (B)-(-2)n-1
(C)(-2)n (D)-(-2)n