数列〔an〕的各项都是正数,其前n项和为Sn满足an+Sn=4.求数列an的通项公式②设bn=〔1/(2-log2an)〕^2,{bn}的前n项和为Tn,证当n≧2时Tn
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![数列〔an〕的各项都是正数,其前n项和为Sn满足an+Sn=4.求数列an的通项公式②设bn=〔1/(2-log2an)〕^2,{bn}的前n项和为Tn,证当n≧2时Tn](/uploads/image/z/1389213-45-3.jpg?t=%E6%95%B0%E5%88%97%E3%80%94an%E3%80%95%E7%9A%84%E5%90%84%E9%A1%B9%E9%83%BD%E6%98%AF%E6%AD%A3%E6%95%B0%2C%E5%85%B6%E5%89%8Dn%E9%A1%B9%E5%92%8C%E4%B8%BASn%E6%BB%A1%E8%B6%B3an%2BSn%3D4.%E6%B1%82%E6%95%B0%E5%88%97an%E7%9A%84%E9%80%9A%E9%A1%B9%E5%85%AC%E5%BC%8F%E2%91%A1%E8%AE%BEbn%3D%E3%80%941%2F%EF%BC%882-log2an%EF%BC%89%E3%80%95%5E2%2C%7Bbn%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%E4%B8%BATn%2C%E8%AF%81%E5%BD%93n%E2%89%A72%E6%97%B6Tn)
数列〔an〕的各项都是正数,其前n项和为Sn满足an+Sn=4.求数列an的通项公式②设bn=〔1/(2-log2an)〕^2,{bn}的前n项和为Tn,证当n≧2时Tn
数列〔an〕的各项都是正数,其前n项和为Sn满足an+Sn=4.求数列an的通项公式
②设bn=〔1/(2-log2an)〕^2,{bn}的前n项和为Tn,证当n≧2时Tn
数列〔an〕的各项都是正数,其前n项和为Sn满足an+Sn=4.求数列an的通项公式②设bn=〔1/(2-log2an)〕^2,{bn}的前n项和为Tn,证当n≧2时Tn
n=1,a1=2,
n>1,an-1+Sn-1=4(1)
an-Sn=4 (2) (2)-(1) an/an-1=1/2,an=2x(1/2)^(n-1)=0.5^(n-2) n为正整数
(2)补充问题你在检查一下,该题考点不等式放缩