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总题量:517 选择本页全部试题
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)满足\(a_{1}=1\),\(a_{2}=3\),\(a_{n+2}=3a_{n+1}-2a_{n}(n\in N^{*})\),
    \((Ⅰ)\)证明:数列\(\{a_{n+1}-a_{n}\}\)是等比数列;
    \((Ⅱ)\)求数列\(\{a_{n}\}\)的通项公式.
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    设等差数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),且\(a_{5}+a_{13}=34\),\(S_{3}=9.\)
    \((Ⅰ)\)求数列\(\{a_{n}\}\)的通项公式\(a_{n}\)及前\(n\)项和公式\(S_{n}\)
    \((Ⅱ)\)求证:\(\dfrac{1}{S_{1}}+\dfrac{1}{S_{2}}+…+\dfrac{1}{S_{n}}< 2.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),满足\(S_{n}+a_{n}=1.\)
    \((1)\)求数列\(\{a_{n}\}\)的通项公式;
    \((2)\)记\(b_{n}=\dfrac{a_{n}}{(a_{n}+1)(a_{n+1}+1)}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    设等差数列\(\{a_{n}\}\)的公差为\(d\),\(d\)为整数,前\(n\)项和为\(S_{n}\),等比数列\(\{b_{n}\}\)的公比为\(q\),已知\(a_{1}=b_{1}\),\(b_{2}=2\),\(d=q\),\(S_{10}=100\),\(n\in N^{*}.\)
    \((Ⅰ)\)求数列\(\{a_{n}\}\)与\(\{b_{n}\}\)的通项公式;
    \((Ⅱ)\)求数列\(\{a_{n}+b_{n}\}\)的前\(n\)项和为\(T_{n}\);
    \((Ⅲ)\)设\(c_{n}=\sqrt{\dfrac{a_{n}-n}{a_{n}^{2}}}\),求证:\(c_{1}+c_{2}+c_{3}+⋅⋅⋅+c_{n}< \sqrt {n}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    设\(\{a_{n}\}\)是等差数列,\(\{b_{n}\}\)是等比数列,公比大子\(0\),且\(a_{1}=b_{1}=3\),\(b_{2}=a_{3}\),\(b_{3}=4a_{2}+3.\)
    \((Ⅰ)\)求\(\{a_{n}\}\)和\(\{b_{n}\}\)的通项公式;
    \((Ⅱ)\)设数列\(\{c_{n}\}\)满足\(c_{n}=\begin{cases}{1,n\text{为奇数}}\\ {b_{\frac{n}{2}},n\text{为偶数}}\end{cases}\),求\(\sum\limits_{i=1}^{2n}a_{i}c_{i}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    已知公差不为\(0\)的等差数列\(\{a_{n}\}\)满足\(a_{3}=5\),且\(a_{1}\),\(a_{2}\),\(a_{5}\)成等比数列.
    \((Ⅰ)\)求\(\{a_{n}\}\)的通项公式;
    \((Ⅱ)\)设\(b_{n}=\dfrac{1}{3^{n}}-\dfrac{1}{a_{n}a_{n+1}}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    已知\(\{a_{n}\}\)为等差数列,\(\{b_{n}\}\)为等比数列,且满足\(a_{1}=1\),\(b_{1}=2\),\(a_{4}=4(a_{3}-a_{2})\),\(b_{4}=4(b_{3}-b_{2}).\)
    \((1)\)求\(\{a_{n}\}\)和\(\{b_{n}\}\)的通项公式;
    \((2)\)对任意的正整数\(n\),设\(c_{n}=a_{n}b_{n}\),求数列\(\{c_{n}\}\)的前\(n\)项和\(S_{n}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    在等差数列\(\{a_{n}\}\)中,\(a_{1}=3\),其前\(n\)项和为\(S_{n}\),各项均为正数的等比数列\(\{b_{n}\}\)中,\(b_{1}=1\),且满足\(b_{3}=S_{2}\),\(a_{1}+a_{2}+b_{1}=10.\)
    \((Ⅰ)\)求数列\(\{a_{n}\}\)与\(\{b_{n}\}\)的通项公式;
    \((Ⅱ)\)若数列\(\{\dfrac{1}{S_{n}}\}\)的前\(n\)项和为\(T_{n}\),证明:\(T_{n}< \dfrac {2}{3}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    等比数列\(\{a_{n}\}\)满足\(a_{n}>0\),\(a_{1}=1\),且\(3a_{2}\),\(\dfrac{1}{2}a_{4}\),\(2a_{3}\)成等差数列.
    \((Ⅰ)\)求数列\(\{a_{n}\}\)的通项公式;
    \((Ⅱ)\)记\(b_{n}=\dfrac{2\log_{3}a_{n}+1}{a_{n}}\),数列\(\{b_{n}\}\)的前\(n\)项和为\(S_{n}\),求\(S_{n}.\)
  • 题型:解答题 题类:模拟题 难易度:较易

    年份:2021

    已知数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),\(a_{1}=1\),\(a_{2}=2\),公比为\(2\)的等比数列\(\{b_{n}\}\)的前\(n\)项和为\(T_{n}\),并且满足\(a_{n+1}\log_{2}(T_{n}+1)=2S_{n}.\)
    \((Ⅰ)\)求数列\(\{a_{n}\}\),\(\{b_{n}\}\)的通项公式;
    \((Ⅱ)\)已知\(c_{n}=\dfrac{a_{n-1}a_{2^{n}}+1}{T_{n}T_{n+1}}\),规定\(a_{0}=0\),若存在\(n\in N^{*}\)使不等式\(c_{1}+c_{2}+c_{3}+⋅⋅⋅+c_{n}< 1-\dfrac{λ}{n}\)成立,求实数\(λ\)的取值范围.