职教组卷基于海量职教高考试题库建立的在线组卷及学习系统
职教组卷
  • 题型:解答题 题类:其他 难易度:较易

    设数列\(\{a_{n}\}\)满足:\(a_{1}=1\),\(a_{n+1}=3a_{n}\),\(n∈N_{+}\).
    \((\)Ⅰ\()\)求\(\{a_{n}\}\)的通项公式及前\(n\)项和\(S_{n}\);
    \((\)Ⅱ\()\)已知\(\{b_{n}\}\)是等差数列,\(T_{n}\)为前\(n\)项和,且\(b_{1}=a_{2}\),\(b_{3}=a_{1}+a_{2}+a_{3}\),求\(T_{20}\).
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