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            • 1.

              已知数列\(\{a_{n}\}\)满足\(n{a}_{n}-\left(n+1\right){a}_{n-1}=2{n}^{2}+2n(n=2,3,4...),{a}_{1}=6 \)

              \((1)\)求证\(\left\{ \dfrac{{a}_{n}}{n+1}\right\} \)为等差数列,并求出\(\{a\)\(n\)\(\}\)的通项公式

              \((2)\)数列\(\left\{ \dfrac{1}{{a}_{n}}\right\} \)的前\(n\)项和\(S_{n,}\)求求证:\({S}_{n} < \dfrac{5}{12} \)

            • 2.

              在等比数列\(\left\{ {{a}_{n}} \right\}\)中,\(3{{a}_{1}},\dfrac{1}{2}{{a}_{5}},2{{a}_{3}}\)成等差数列,则\(\dfrac{{{a}_{9}}+{{a}_{10}}}{{{a}_{7}}+{{a}_{8}}}=\)             

            • 3.
              \(\{a_{n}\}\)是等差数列,且\(a_{1}+a_{4}+a_{7}=45\),\(a_{2}+a_{5}+a_{8}=39\),则\(a_{3}+a_{6}+a_{9}\)的值是\((\)  \()\)
              A.\(24\)
              B.\(27\)
              C.\(30\)
              D.\(33\)
            • 4.

              已知\(f(x)\) 是定义在\(R\) 上的不恒为零的函数,且对于任意的\(a,b∈R \),满足\(f(a,b)=af(b)+bf(a) \),\(f(2)=2\),数列\(\left\{ {{a}_{n}} \right\}\) 满足\({a}_{n}= \dfrac{f({2}^{n})}{{2}^{n}}(n∈{N}^{*}) \)

              \((1)\)求数列\(\left\{ {{a}_{n}} \right\}\) 的通项公式;

              \((2)\)若存在正整数\(n\in [1,10]\) ,使得\(m{{a}_{n}}^{2}+2{{a}_{n}}-2m-1 < 0\) 成立,求实数\(m\) 的取值范围。

            • 5.

              若存在常数\(k\left( k\in {{N}^{*}},k\geqslant 2 \right)\)\(q\)\(d\),使得无穷数列\(\left\{ {{a}_{n}} \right\}\)满足\({{a}_{n+1}}=\begin{cases} {{a}_{n}}+d,\dfrac{n}{k}\notin {{N}^{*}} \\ q{{a}_{n}},\dfrac{n}{k}\in {{N}^{*}} \\\end{cases}\)则称数列\(\left\{ {{a}_{n}} \right\}\)为“段比差数列”,其中常数\(k\)\(q\)\(d\)分别叫做段长、段比、段差\(.\)设数\(\left\{ {{b}_{n}} \right\}\)为“段比差数列”,它的首项、段长、段比、段差分别为\(1\)、\(3\)、\(q\)、\(3\).

                \((1)\)当\(q=0\)时,求\({{b}_{2014}}\),\({{b}_{2016}}\);

                \((2)\)当\(q=1\)时,设\(\left\{ {{b}_{n}} \right\}\)的前\(3n\)项和为\({{S}_{3n}}\),

                     \(①\)证明:\(\left\{ {{b}_{3n-1}} \right\}\)为等差数列;

                     \(②\)证明:\({{b}_{3n-2}}+{{b}_{3n}}=2{{b}_{3n-1}}\);

                     \(③\)若不等式\({{S}_{3n}}\leqslant \lambda \cdot {{3}^{n-1}}\)对\(n\in {{N}^{*}}\)恒成立,求实数\(\lambda \)的取值范围;

            • 6. 已知\(\{a_{n}\}\)是等差数列,且\(a_{2}+a_{5}+a_{8}+a_{11}=48\),则\(a_{6}+a_{7}=(\)  \()\)
              A.\(12\)
              B.\(16\)
              C.\(20\)
              D.\(24\)
            • 7.

              已知首项都是\(1\)的两个数列\(\left\{ {{a}_{n}} \right\},\left\{ {{b}_{n}} \right\}({{b}_{n}}\ne 0),n\in {{N}^{*}})\)满足\({{a}_{n}}{{b}_{n+1}}-{{a}_{n+1}}{{b}_{n}}+2{{b}_{n+1}}{{b}_{n}}=0.\)

              \((1)\)令\({{c}_{n}}=\dfrac{{{a}_{n}}}{{{b}_{n}}},\)求数列\(\left\{ {{c}_{n}} \right\}\)的通项公式;

              \((2\)若\({{b}_{n}}={{3}^{{n}}},\)求数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和\({{S}_{{n}}}\) .

            • 8.

              在数列\(\{\)\(a_{n}\)\(\}\)中,\(a\)\({\,\!}_{1}=1\),\(3\)\(a_{n}a_{n}\)\({\,\!}_{-1}+\)\(a_{n}\)\(-\)\(a_{n}\)\({\,\!}_{-1}=0(\)\(n\)\(\geqslant 2\),\(n\)\(∈N^{*}).\)

              \((1)\)求证:数列\(\left\{\begin{matrix} \dfrac{1}{a_{n}}\end{matrix}\right\}\)是等差数列;

              \((2)\)求数列\(\{\)\(a_{n}\)\(\}\)的通项公式;

              \((3)\)求数列\(\{a_{n}a_{n+1}\}\)的前\(n\)项和\(T_{n}\)

            • 9.

              数列\(\{{{a}_{n}}\}\)中,\({{a}_{1}}=1,{{a}_{n+1}}\cdot {{a}_{n}}+{{a}_{n+1}}-{{a}_{n}}=0,\)设\({{b}_{n}}=\dfrac{1}{{{a}_{n}}}\),

               \((1)\)证明数列\(\{{{b}_{n}}\}\)是等差数列,并求数列\(\{{{a}_{n}}\}\)的通项公式;

               \((2)\)设\({{c}_{n}}=[\dfrac{2{{b}_{n}}+3}{5}],\)求数列\(\{{{c}_{n}}\}\)的前\(8\)项和\({{S}_{n}}\),其中\([x]\)表示不超过\(x\)的最大整数,如\([0.9]=0,[2.6]=2\)。

            • 10.

              己知数列\(\{a_{n}\}\),\(a_{1}=1\),\(a_{n+1} > a_{n}\),\((a_{n}+a_{n+1}-1)^{2}=4a_{n}a_{n+1}(n∈N^{*}).\)

              \((1)\)求数列\(\{a_{n}\}\)的通项公式;

              \((2)\)记\({{b}_{n}}=\dfrac{1}{\sqrt[4]{{{a}_{n}}}}\),\(T_{n}=b_{1}+b_{2}+…+b_{n}\),估算\(T_{2017}\)的整数部分.

              \((\)参考数据:\(1.41 < \sqrt{2} < 1.42\),\(44.92 < \sqrt{2018} < 45)\)

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