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:期中考试 难易度:较易

    已知数列\(\{a_{n}\}\),\(\{b_{n}\}\),\(S_{n}\)为数列\(\{a_{n}\}\)的前\(n\)项和,\(a_{2}=4b_{1}\),\(S_{n}=2a_{n}-2\),\(nb_{n+1}-(n+1)b_{n}=n^{2}+n(n\in N^{*})\)
    \((Ⅰ)\)求数列\(\{a_{n}\}\)的通项公式;
    \((Ⅱ)\)证明\(\{\dfrac{b_{n}}{n}\}\)为等差数列;
    \((Ⅲ)\)若数列\(\{c_{n}\}\)的通项公式为\(c_{n}=\begin{cases}-\dfrac{a_{n}b_{n}}{2},n\text{为奇数}\\ \dfrac {a_{n}b_{n}}{4},n\text{为偶数}\end{cases}\),令\(T_{n}\)为\(\{c_{n}\}\)的前\(n\)项的和,求\(T_{2n}.\)
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