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            • 1.
              数列\(\{a_{n}\}\)中\(a_{1}= \dfrac {1}{2}\),前\(n\)项和\(S_{n}=n^{2}a_{n}-n(\;n-1\;)\),\(n=1\),\(2\),\(…\).
              \((1)\)证明数列\(\{\; \dfrac {n+1}{n}S_{n}\}\)是等差数列;
              \((2)\)求\(S_{n}\)关于\(n\)的表达式;
              \((3)\)设 \(b_{n}= \dfrac {1}{n^{3}}S_{n}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}\).
            • 2.

              \((1)\)在\(\triangle ABC\)中,已知\(a=x,b=2,B=60^{\circ}\),如果\(\triangle ABC\) 两组解,则\(x\)的取值范围是_________

              \((2).\)一凸\(n\)边形,各内角的度数成等差数列,公差是\({{10}^{\circ }}\),最小内角是\({{100}^{\circ }}\),则边数\(n=\)______________


              \((3).\)有一解三角形的题因纸张破损,有一条件不清,且具体如下:在\(\Delta ABC\)中,已知\(a=\sqrt{3}{{,}^{{}}}B={{45}^{\circ }}\),____________,求角\(A.\) 经推断破损处的条件为三角形一边的长度,且答案提示\(A=60^{\circ}\),试将条件补充完整.


              \((4).\)一个由若干行数字组成的数表,从第二行起每一行中的数字均等于其肩上的两个数之和,最后一行仅有一个数,第一行是前\(100\)个正整数按从小到大排成的行,则最后一行的数是_________\((\)可以用指数表示\()\)

            • 3.

              设各项均为正数的数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),满足\(4{{S}_{n}}=a_{^{_{n+1}}}^{2}-4n-1\),且\({{a}_{1}}=1\),公比大于\(1\)的等比数列\(\left\{ {{b}_{n}} \right\}\)满足\({{b}_{2}}=3\),\({{b}_{1}}+{{b}_{3}}=10\).

              \((1)\)求证数列\(\left\{ {{a}_{n}} \right\}\)是等差数列,并求其通项公式;

              \((2)\)若\({{c}_{n}}=\dfrac{{{a}_{n}}}{3{{b}_{n}}}\),求数列\(\left\{ {{c}_{n}} \right\}\)的前\(n\)项和\({{T}_{n}}\);

              \((3)\)在\((2)\)的条件下,若\({{c}_{n}}\leqslant {{t}^{2}}+\dfrac{4}{3}t-2\)对一切正整数\(n\)恒成立,求实数\(t\)的取值范围.

            • 4.
              已知等差数列\(\{a_{n}\}\)的公差\(d\neq 0\),它的前\(n\)项和为\(S_{n}\),若\(S_{5}=70\),且\(a_{2}\),\(a_{7}\),\(a_{22}\)成等比数列.
              \((1)\)求数列\(\{a_{n}\}\)的通项公式;

              \((2)\)设数列\(\left\{ \dfrac{1}{{S}_{n}}\right\} \)的前\(n\)项和为\(T_{n}\),求证:\(T_{n} < \dfrac{3}{8} \).

            • 5.

              若各项均为正数的数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),且\(2 \sqrt[]{S_{n}}=a_{n}+1 (n∈N*)\).

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

              \((2)\)若正项等比数列\(\{b_{n}\}\),满足\(b_{2}=2\),\(2b_{7}+b_{8}=b_{9}\),求\(T_{n}=a_{1}b_{1}+a_{2}b_{2}+…+a_{n}b_{n}\);

              \((3)\)对于\((2)\)中的\(T_{n}\),若对任意的\(n∈N^{*}\),不等式\(λ·(-1)^{n} < \dfrac{1}{2^{n+1}}(T_{n}+21)\)恒成立,求实数\(λ\)的取值范围.

            • 6.

              设数列\(\{a_{n}\}\)为等差数列,数列\(\{b_{n}\}\)为等比数列\(.\)若\(a_{1} < a_{2}\),\(b_{1} < b_{2}\),且\({b}_{i}={{a}_{i}}^{2}(i=1,2,3) \),则数列\(\{b_{n}\}\)的公比为________.

            • 7. 已知数列\(\{a_{n}\}\)满足\(a_{1}=1\),\(a_{n}= \dfrac {a_{n-1}}{2a_{n-1}+1}(n∈N^{*},n\geqslant 2)\),数列\(\{b_{n}\}\)满足关系式\(b_{n}= \dfrac {1}{a_{n}}(n∈N^{*}).\)
              \((1)\)求证:数列\(\{b_{n}\}\)为等差数列;
              \((2)\)求数列\(\{a_{n}\}\)的通项公式.
            • 8.

              \(\Delta ABC\)的三个内角分别为\(A\),\(B\),\(C\),则“\(B{=}\dfrac{\pi }{3}\)”是“\(A\),\(B\),\(C\)成等差数列”的\((\)    \()\)

              A.充分而不必要条件                      
              B.必要而不充分条件  
              C.充要条件
              D.既不充分也不必要条件
            • 9.

              给出下列四个关于数列命题:

              \((1)\)若\(\left\{ {{a}_{n}} \right\}\)是等差数列,则三点\(\left( 10,\dfrac{{{S}_{10}}}{10} \right)\)、\(\left( 100,\dfrac{{{S}_{100}}}{100} \right)\)、\(\left( 110,\dfrac{{{S}_{110}}}{110} \right)\)共线;

              \((2)\)若\(\left\{ {{a}_{n}} \right\}\)是等比数列,则\({{S}_{m}}\)、\({{S}_{2m}}-{{S}_{m}}\)、\({{S}_{3m}}-{{S}_{2m}}\) \((m\in {{N}^{*}})\)也是等比数列;

              \((3)\)等比数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),若对任意的\(n\in {{N}^{*}}\),点\(\left(n,{S}_{n}\right) \)均在函数\(y={{b}^{x}}+r\) \((b\ne 0,b\ne {1}, b.r\)均为常数\()\)的图象上,则\(r\)的值为\(-{1}\).

              \((4)\)对于数列\(\left\{ {{a}_{n}} \right\}\),定义数列\(\left\{{a}_{n+1}-{a}_{n}\right\} \)为数列\(\left\{ {{a}_{n}} \right\}\)的“差数列”,若\({{a}_{{1}}}{=2}\),\(\left\{ {{a}_{n}} \right\}\)的“差数列”的通项为\({{{2}}^{n}}\),则数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和\({{S}_{n}}\) \(={{2}^{n+1}}-2\)

              其中正确命题的个数是\((\)      \()\)

              A.\(4\)   
              B.\(3\)   
              C.\(2\)   
              D.\(1\)
            • 10.

              已知数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),且\(S_{n}+2n=3n^{2}\).

              \((1)\)求证:数列\(\{a_{n}\}\)为等差数列;

              \((2)\)若\({{b}_{n}}=\dfrac{3}{{{a}_{n}}{{a}_{n+1}}}\),求数列\(\{b_{n}\}\)前\(n\)项和\(T_{n}\).

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