等差数列{an}的前n项和为Sn,若a3+a7+a11=6,则S13=______.
设等差数列{an}的前n项和为Sn,且a5=3a7,则S9/S13=?
设等差数列{an}的前n项和为Sn,若a3=12,S12>0,S13
等差数列{an}中,a3+a7-a10=8,a11-a4=4.记Sn=a1+a2+…+an,则S13等于______.
来达人~~数列Sn是等差数列An的前n项和 ~~若A7/A4=2则 S13/S7=?2.等差数列An中 A1+A4+A1
设等差数列{an}的前n项和sn,已知a3=12,s12>0.s13
等差数列{an}的前n项和Sn已知a3=12,S12>0,S13
设等差数列{an}的前n项和为Sn,若a1=-11,a3+a7=-6,则当Sn取最小值时,n等于( )
设等差数列{an}的前n项的和为Sn,已知a3=12,S12>0,S13
设等差数列{an}的前n项和为Sn,已知a3=12,S12>0,S13<0
设等差数列{an}的前n项和为Sn,已知a3=12,S12>0,S13
设等差数列{an}的前n项和为Sn,已知a3=12,S12>0,S130,S13
设等差数列an 的前n项和为sn已知a3=12 S12>0 S13