问题标题:
设数列an的首项a1=3/2,前n项和为Sn,且满足2an+1+Sn=3(n∈N*),求an及Sn注意n和n+1为小下标
问题描述:
设数列an的首项a1=3/2,前n项和为Sn,且满足2an+1+Sn=3(n∈N*),求an及Sn注意n和n+1为小下标
陆鹏回答:
2a(n+2)+s(n+1)=32a(n+1)+sn=3相减:2a(n+2)-2a(n+1)+a(n+1)=02a(n+2)=a(n+1)即:a(n+2)/a(n+1)=1/2=q……公比(an为等比数列n≥2)再由:2a2+s1=3,即:2a2+a1=32a3+s2=3,即:2a3+a2+a1=3a1=3/2a2=3/4a3=3/8于是,立...
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