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            • 1.

              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________.

            • 2. 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.
            • 3.

              \(\Delta ABC\)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
            • 4.

              设\({{S}_{n}}\)是等差数列\(\left\{ a{}_{n} \right\}\)的前\(n\)项和,若\( \dfrac{{a}_{5}}{{a}_{3}}= \dfrac{5}{9}, \)则\( \dfrac{{S}_{9}}{{S}_{5}} =(\)   \()\)

              A.\(1\)
              B.\(-1\)
              C.\(2\)
              D.\(\dfrac{1}{2}\)
            • 5.

              已知方程\(\left({x}^{2}-2x+m\right)\left({x}^{2}-2x+n\right)=0 \)的四个根组成一个首项为\( \dfrac{1}{4} \)的等差数列,则\(\left|m-n\right| \)等于

              A.\(1\)
              B. \( \dfrac{3}{4} \)
              C. \( \dfrac{1}{2} \)
              D. \( \dfrac{3}{8} \)
            • 6. 若数列\(\{a_{n}\}\)满足条件:存在正整数\(k\),使得\(a_{n+k}+a_{n-k}=2a_{n}\)对一切\(n∈N^{*}\),\(n > k\)都成立,则称数列\(\{a_{n}\}\)为\(k\)级等差数列.
              \((1)\)已知数列\(\{a_{n}\}\)为\(2\)级等差数列,且前四项分别为\(2\),\(0\),\(4\),\(3\),求\(a_{8}+a_{9}\)的值;
              \((2)\)若\(a_{n}=2n+\sin ωn(ω\)为常数\()\),且\(\{a_{n}\}\)是\(3\)级等差数列,求\(ω\)所有可能值的集合,并求\(ω\)取最小正值时数列\(\{a_{n}\}\)的前\(3n\)项和\(S_{3n}\);
              \((3)\)若\(\{a_{n}\}\)既是\(2\)级等差数列\(\{a_{n}\}\),也是\(3\)级等差数列,证明:\(\{a_{n}\}\)是等差数列.
            • 7.

              已知在等比数列\(\{{{a}_{n}}\}\)中,\({{a}_{1}}=1\),且\({{a}_{2}}\)是\({{a}_{1}}\)和\({{a}_{3}}-1\)的等差中项.

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

              \((2)\)若数列\(\{{{b}_{n}}\}\)满足\({{b}_{n}}=2n+{{a}_{n}}(n\in {{N}^{*}})\),求\(\{{{b}_{n}}\}\)的前\(n\)项和\({{S}_{n}}\).

            • 8.

              在等差数列\(\{a_{n}\}\)中,\(a_{2}=5\),\(a_{5}=11\),数列\(\{b_{n}\}\)的前\(n\)项和\(S_{n}=n^{2}+a_{n}\).

              \((\)Ⅰ\()\)求数列\(\{a_{n}\}\),\(\{b_{n}\}\)的通项公式;

              \((\)Ⅱ\()\)求数列\(\left\{ \dfrac{1}{{{b}_{n}}{{b}_{n+1}}} \right\}\)的前\(n\)项和\(T_{n}\).

            • 9.

              \((1)\)不等式\(\dfrac{1}{x} < 1\)的解集是________.

              \((2)\)已知\(a\),\(b\)是互异的正数,\(A\)是\(a\),\(b\)的等差中项,\(G\)是\(a\),\(b\)的正的等比中项,则\(A\)________\(G( > , < ,\geqslant ,\leqslant \)选填其中一个\()\).

              \((3)\)已知\(\sin (60{}^\circ +\alpha )=\dfrac{5}{13}\),\(30^{\circ} < a < 120^{\circ}\),则\(\cos α=\)________.

              \((4)\)如图在正方体\(ABCD—A_{1}B_{1}C_{1}D_{1}\)中,给出以下结论


              \(①A_{1}C_{1}\)与平面\(A_{1}B_{1}CD\)成\(45^{\circ}\)角;

              \(②CD_{1}\)与\(BC_{1}\)成\(60^{\circ}\)角;

              \(③{{V}_{B1}}_{-{{A}_{1}}B{{C}_{1}}}=\dfrac{1}{2}{{V}_{B}}{{_{1}}_{-A{{D}_{1}}C}}\);

              \(④\)正方体的内切球,与各条棱相切的球,外接球的表而积之比为\(1︰2︰3\)其中正确的结论序号是________\(.(\)写出所有正确结论的序号\()\)

            • 10.

              已知数列\(\left\{ {{a}_{n}} \right\}\),\({{a}_{n}} > 0\),其前\(n\)项和\({{S}_{n}}\)满足\({{S}_{n}}=2{{a}_{n}}-{{2}^{n+1}}\),其中\(n\in N*\).

              \((\)Ⅰ\()\)设\({{b}_{n}}=\dfrac{{{a}_{n}}}{{{2}^{n}}}\),证明:数列\(\left\{ {{b}_{n}} \right\}\)是等差数列;

              \((\)Ⅱ\()\)设\({{c}_{n}}={{b}_{n}}\cdot {{2}^{-n}}\),\({{T}_{n}}\)为数列\(\left\{ {{c}_{n}} \right\}\)的前\(n\)项和,求证:\({{T}_{n}} < 3\);

              \((\)Ⅲ\()\)设\({{d}_{n}}={{4}^{n}}+{{(-1)}^{n-1}}\lambda \cdot {{2}^{{{b}_{n}}}}(\lambda \)为非零整数,\(n\in N*)\),试确定\(\lambda \)的值,使得对任意\(n\in N*\),都有\({{d}_{n+1}} > {{d}_{n}}\)成立.

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