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总题量:903 选择本页全部试题
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知\(\{a_{n}\}\)是公差为\(3\)的等差数列,前\(n\)项和为\(S_{n}(n\in N^{*})\),\(\{b_{n}\}\)是首项为\(2\)的等比数列,且公比大于\(0\),\(b_{2}+b_{3}=12\),\(S_{11}=11b_{4}.\)
    \((1)\)求\(\{a_{n}\}\)和\(\{b_{n}\}\)的通项公式;
    \((2)\)求\(\{a_{n}b_{n}\}\)的前\(n\)项和\(T_{n}\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    在等差数列\(\{a_{n}\}\)中,\(S_{n}\)是数列\(\{a_{n}\}\)的前\(n\)项和,已知\(a_{2}=4\),\(S_{4}=20.\)
    \((1)\)求\(\{a_{n}\}\)的通项公式;
    \((2)\)若______,求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}.\)
    \((\)在①\(b_{n}=\dfrac{4}{a_{n}a_{n+1}}\);②\(b_{n}=(-1)^{n}\boldsymbol{⋅}a_{n}\)两个条件中选择一个补充在第\((2)\)问中,并对其求解,如果多写,按第一个计分\()\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),且满足\(S_{n}=3-2a_{n}.\)
    \((1)\)求证:\(\{a_{n}\}\)是等比数列;
    \((2)\)求数列\(\{na_{n}\}\)的前\(n\)项和\(T_{n}.\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知正项数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),且满足\(a_{1}=1\),\(a_{n+1}^{2}=S_{n+1}+S_{n}.\)
    \((1)\)求数列\(\{a_{n}\}\)的通项公式;
    \((2)\)设\(b_{n}=\dfrac{1}{(2a_{n}-1)(2a_{n}+1)}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}.\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    数列\(\{a_{n}\}\)的各项均为正数,其前\(n\)项和为\(S_{n}\),\(a_{1}=1\),且\(S_{n}+S_{n+1}=a_{n+1}^{2}.\)
    \((1)\)证明:数列\(\{a_{n}\}\)为等差数列;
    \((2)\)若数列\(\{b_{n}\}\)满足\(b_{n}+b_{n+1}=a_{n}\),求数列\(\{b_{n}\}\)的前\(2n\)项和\(T_{2n}.\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)的前\(n\)项和\(S_{n}\)满足\(2S_{n}-na_{n}=n\),\(n\in N^{+}\),且\(a_{2}=3.\)
    \((1)\)求数列\(\{a_{n}\}\)的通项公式;
    \((2)\)设\(b_{n}=\dfrac{1}{a_{n}\sqrt{a_{n+1}}+a_{n+1}\sqrt{a_{n}}}\),\(T_{n}\)为数列\(\{b_{n}\}\)的前\(n\)项和,求使\(T_{n}>\dfrac{9}{20}\)成立的最小正整数\(n\)的值.
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知各项均为正数的等比数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),若\(S_{3}=39\),且\(3a_{3}\)是\(a_{5}\)与\(-a_{4}\)的等差中项.
    \((1)\)求数列\(\{a_{n}\}\)的通项公式;
    \((2)\)若数列\(\{b_{n}\}\)的前\(n\)项和为\(T_{n}\),且\(b_{n}=4\log_{3}a_{n}\),求\(\dfrac{1}{T_{1}}+\dfrac{1}{T_{2}}+\dfrac{1}{T_{3}}+⋯+\dfrac{1}{T_{n}}.\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),且\(\{\dfrac{S_{n}}{n}\}\)是等差数列,\(a_{1}=2\),\(a_{2}=4.\)
    \((1)\)求数列\(\{a_{n}\}\)的通项公式;
    \((2)\)若数列\(\{b_{n}\}\)满足\(b_{n}=\dfrac{1}{(a_{n}-1)(2n+1)}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}.\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    记数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),若对于任意的正整数\(n\),都有\(S_{n}=\dfrac{3}{2}a_{n}-2n.\)
    \((Ⅰ)\)求\(a_{1}\),\(a_{2}\);
    \((Ⅱ)\)设\(b_{n}=a_{n}+2\),求证:数列\(\{b_{n}\}\)是等比数列;
    \((Ⅲ)\)求数列\(\{a_{n}\}\)的前\(n\)项和\(S_{n}.\)
  • 题型:解答题 题类:期末考试 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)各项都是正数,\(a_{1}=1\),对任意\(n\in N*\)都有\(a_{1}^{2}+a_{2}^{2}+\)…\(+a_{n}^{2}=\dfrac{a_{n+1}^{2}-1}{3}.\)数列\(\{b_{n}\}\)满足\(b_{1}=1\),\(nb_{n+1}=(n+1)b_{n}+n(n+1).\)
    \((1)\)求数列\(\{a_{n}\}\),\(\{b_{n}\}\)的通项公式;
    \((2)\)数列\(\{c_{n}\}\)满足\(c_{n}=\dfrac{\sqrt{b_{n}}}{a_{n}}\),数列\(\{c_{n}\}\)的前\(n\)项和为\(T_{n}\),若不等式\(λ\boldsymbol{⋅}2^{n}>T_{n}+\dfrac{n}{2^{n-1}}\)对一切\(n\in N*\)恒成立,求\(λ\)的取值范围.