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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. 已知数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),对任意\(n∈N*\),点\(\left( n,{{S}_{n}} \right)\)都在函数\(f\left( x \right)=2{{x}^{2}}-x\)的图象上.
              \((1)\)求数列\(\left\{ {{a}_{n}} \right\}\)的通项公式;
              \((2)\)设\({{b}_{n}}=\dfrac{{{S}_{n}}}{n+p}\),且数列\(\left\{ {{b}_{n}} \right\}\)是等差数列,求非零常数\(p\)的值;
              \((3)\)设\({{c}_{n}}=\dfrac{2}{{{a}_{n}}{{a}_{n+1}}}\),\({{T}_{n}}\)是数列\(\left\{ {{c}_{n}} \right\}\)的前\(n\)项和,求使得\({{T}_{n}} < \dfrac{m}{20}\)对所有\(n∈N*\)都成立的最小正整数\(m\).
            • 3.

              \((1)\)已知\(-1,{{a}_{1}},{{a}_{2}},{{a}_{3}},-9\)五个实数成等差数列,\(-1\),\(b1\),\(b2\),\(b3\),\(-9\)五个实数成等比数列,则\((a1-a3)/b2\)等于_______ .

              \((2)\dfrac{\sin 160{}^\circ }{\sin 110{}^\circ }-\tan 320^{\circ}+\sqrt{3}\tan 20^{\circ}\tan 40^{\circ}=\)______.

              \((3)\)已知集合\(A=\{\left. x \right|{{x}^{2}}-16 < 0\}\),\(B=\{x\left| {{x}^{2}}-4x+3 > 0 \right.\}\),则\(A∩B=\)_________.

              \((4)\)如图,测量河对岸的塔高\(AB\)时,可以选与塔底在同一水平面内的两个测点\(C\)与\(D\),测得,测得\(∠BCD=75^{\circ}\),\(CD=60\),\(∠BDC=60^{\circ}\),并在点\(C\)测得塔顶\(A\)的仰角为\(60^{\circ}\),则塔高\(AB=\)________\(m\).

            • 4.
              设数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),若对任意的正整数\(n\),总存在正整数\(m\),使得\(S_{n}=a_{m}\),则称\(\{a_{n}\}\)是“\(H\)数列”.
              \((1)\)若数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}=2^{n}(n∈N^{*})\),证明:\(\{a_{n}\}\)是“\(H\)数列”;
              \((2)\)设\(\{a_{n}\}\)是等差数列,其首项\(a_{1}=1\),公差\(d < 0\),若\(\{a_{n}\}\)是“\(H\)数列”,求\(d\)的值;
              \((3)\)证明:对任意的等差数列\(\{a_{n}\}\),总存在两个“\(H\)数列”\(\{b_{n}\}\)和\(\{c_{n}\}\),使得\(a_{n}=b_{n}+c_{n}(n∈N^{*})\)成立.
            • 5. 数列{an}中,a3=2,a7=1,若为等差数列,则a11=(  )
              B.
              C.
              D.2
            • 6.
              \(\{a_{n}\}\)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.\(33\)
            • 7.
              已知数列\(\{a_{n}\}\),\(\{b_{n}\}\)满足\(b_{n}=a_{n+1}-a_{n}(n=1,2,3,…)\).
              \((1)\)若\(b_{n}=10-n\),求\(a_{16}-a_{5}\)的值;
              \((2)\)若\(b_{n}=(-1)^{n}(2^{n}+2^{33-n})\)且\(a_{1}=1\),则数列\(\{a_{2n+1}\}\)中第几项最小?请说明理由;
              \((3)\)若\(c_{n}=a_{n}+2a_{n+1}(n=1,2,3,…)\),求证:“数列\(\{a_{n}\}\)为等差数列”的充分必要条件是“数列\(\{c_{n}\}\)为等差数列且\(b_{n}\leqslant b_{n+1}(n=1,2,3,…)\)”.
            • 8.

              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。

            • 9.

              已知数列\(\{a_{n}\}\)满足:\(a_{1}=1\),\(a_{2}=2\),\({{a}_{n+2}}=(1+{{\cos }^{2}}\dfrac{n\pi }{2}){{a}_{n}}+{{\sin }^{2}}\dfrac{n\pi }{2}\),\(n=1\),\(2\),\(3\),\(…\)

              \((\)Ⅰ\()①\)求\(a_{3}\),\(a_{4}\),\(a_{5}\),\(a_{6}\);

              \(②\)证明数列\(a_{1}\),\(a_{3}\),\(a_{5}\),\(a_{7}\),\(…\),\(a_{2k-1}\),\(…(k∈N^{*})\)成等差数列

              \((\)Ⅱ\()\)设\({{b}_{n}}=\dfrac{1}{{{a}_{2n-1}}\cdot \sqrt{{{a}_{2n+1}}}+{{a}_{2n+1}}\cdot \sqrt{{{a}_{2n-1}}}}\),若\(T_{n}=b_{1}+b_{2}+…+b_{n}\),求\(T_{n}\)

            • 10. 在等差数列{an}中,其前n项和记为Sn
              (1)若S101=0,则a51= ______
              (2)若6S5-5S3=5,则a4= ______
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