a1+a5=2a3=0
所以a3=0
a9+a3=2a6=20+0=20
所以a6=10
S11=a6*11=10*11=110
已知等差数列{an}的前n项和为Sn,a1+a5=0,a9=20,则S11=
已知等差数列{an}的前n项和为Sn,a1+a5=0,a9=20,则S11=
数学人气:522 ℃时间:2020-01-28 06:37:08
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