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            • 1.

              已知等差数列\(\left\{ {{a}_{n}} \right\}\)中公差\(d\ne 0\),有\({a}_{1}+{a}_{4}=14,且{a}_{1},{a}_{2},{a}_{7} \)成等比数列.

              \((\)Ⅰ\()\)求\(\left\{ {{a}_{n}} \right\}\)的通项公式\(a_{n}^{{}}\)与前\(n\)项和公式\({{S}_{n}}\);

              \((\)Ⅱ\()\)令\({{b}_{n}}=\dfrac{{{S}_{n}}}{n+k}\left( k\ne 0 \right)\),若\(\left\{ {{b}_{n}} \right\}\)是等差数列,求数列\(\left\{ \dfrac{1}{{{b}_{n}}{{b}_{n+1}}} \right\}\)的前\(n\)项和为\({{T}_{n}}\),

            • 2.

              已知函数\(f(x)=4x+1\),\(g(x)=2x\),\(x∈R\),数列\(\{a_{n}\}\),\(\{b_{n}\}\),\(\{c_{n}\}\)满足条件:\(a_{1}=1\),\(a_{n}=f(b_{n})=g(b_{n+1})(n∈N^{*})\),\({{c}_{n}}=\dfrac{1}{[\dfrac{1}{2}f(n)+\dfrac{1}{2}][g(n)+3]}\).

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

              \((\)Ⅱ\()\)求数列\(\{c_{n}\}\)的前\(n\)项和\(T_{n}\),并求使得\({{T}_{n}} > \dfrac{m}{150}\)对任意\(n∈N^{*}\)都成立的最大正整数\(m\);

              \((\)Ⅲ\()\)求证:\(\dfrac{{{a}_{1}}}{{{a}_{2}}}+\dfrac{{{a}_{2}}}{{{a}_{3}}}+\cdots +\dfrac{{{a}_{n}}}{{{a}_{n+1}}} > \dfrac{n}{2}-\dfrac{1}{3}\).

            • 3.

              设数列\(\{a_{n}\}\)是各项均为正数的等比数列,其前\(n\)项和为\(S_{n}\),若\(a_{1}a_{5}=64\),\(S_{5}-S_{3}=48\).

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

              \((2)\) 对于正整数\(k\),\(m\),\(l(k < m < l)\),求证:“\(m=k+1\)且\(l=k+3\)”是“\(5a_{k}\),\(a_{m}\),\(a_{l}\)这三项经适当排序后能构成等差数列”的充要条件\(;\)

              \((3)\) 设数列\(\{b_{n}\}\)满足:对任意的正整数\(n\),都有\(a_{1}b_{n}+a_{2}b_{n-1}+a_{3}b_{n-2}+…+a_{n}b_{1}=3·2^{n+1}-4n-6\),且集合\(M=\left\{ n\left| \dfrac{b_{n}}{a_{n}}{\geqslant }\lambda\mathrm{{,}}n\mathrm{{∈}}N^{\mathrm{{*}}} \right\} \right.\)中有且仅有\(3\)个元素,试求\(λ\)的取值范围.

            • 4. 设\(\{a_{n}\}\)是公差不为\(0\)的等差数列,\(a_{1}=4\)且\(a_{1}\),\(a_{3}\),\(a_{6}\)成等比数列,则\(\{a_{n}\}\)的前\(n\)项和\(S_{n}=\) ______ .
            • 5.

              在等差数列\(\left\{ {{a}_{n}} \right\}\)中,\({{a}_{1}}=3\),其前\(n\)项和为\({{S}_{n}}\),等比数列\(\left\{ {{b}_{n}} \right\}\)的各项均为正数,\({{b}_{1}}=1\),公比为\(q\),且\({{b}_{2}}+{{S}_{2}}=12,q=\dfrac{{{S}_{2}}}{{{b}_{2}}}\)

              \((1)\)求\({{a}_{n}}\)与\({{b}_{n}}\);
              \((2)\)设\({{T}_{n}}={{a}_{n}}{{b}_{1}}+{{a}_{n-1}}{{b}_{2}}+...+{{a}_{1}}{{b}_{n}},n\in {{N}^{+}}\),求\({{T}_{n}}\).
            • 6.

              设等差数列\(\left\{ {{a}_{n}} \right\}\)的公差为\(d\),前\(n\)项和为\({S}_{n},{S}_{n}={n}_{2}+n\left({a}_{1}-1\right)\left(n∈{N}^{*}\right), \) \(且{a}_{1},{a}_{3}-1, {{a}_{5}}+7\)成等比数列.

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

              \((\)Ⅱ\()\)设\({{b}_{n}}=\dfrac{1}{{{a}_{n}}{{a}_{n+1}}}\),求数列\(\left\{ {{b}_{n}} \right\}\)的前\(n\)项和\({{T}_{n}}\).

            • 7.

              已知公差不为\(0\)的等差数列\(\left\{ {{a}_{n}} \right\}\),若\({{a}_{2}}+{{a}_{4}}=10\),且\({{a}_{1}},{{a}_{2}},{{a}_{5}}\)成等比数列,则\({{a}_{1}}=\)_________,\({{a}_{n}}=\)_______.

            • 8.

              已知\(\{a_{n}\}\)是等差数列,公差\(d\)不为零,前\(n\)项和是\(S_{n}\),若\(a_{3}\),\(a_{4}\),\(a_{8}\)成等比数列,则\((\)  \()\)

              A.\(a_{1}d > 0\),\(dS_{4} > 0\) 
              B.\(a_{1}d < 0\),\(dS_{4} < 0\) 
              C.\(a_{1}d > 0\),\(dS_{4} < 0\) 
              D.\(a_{1}d < 0\),\(dS_{4} > 0\)
            • 9.

              已知等差数列\(\left\{ {{a}_{n}} \right\}\)的首项\({{a}_{1}}=1\),公差\(d\ne 0\),等比数列\(\left\{ {{b}_{n}} \right\}\)满足\({{a}_{1}}={{b}_{1}}\),\({{a}_{2}}={{b}_{2}}\),\({{a}_{5}}={{b}_{3}}\)

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

              \((2)\)设数列\({{c}_{n}}\)对任意\(n\in {{N}^{*}}\),均有\(\dfrac{{{c}_{1}}}{{{b}_{1}}}+\dfrac{{{c}_{2}}}{{{b}_{2}}}+\cdots +\dfrac{{{c}_{n}}}{{{b}_{n}}}={{a}_{n+1}}\),求数列\(\left\{ {{c}_{n}} \right\}\)的前\(2017\)项和\({{S}_{2017}}\).

            • 10.
              已知数列\(\{a_{n}\}\)为等比数列,且\(a_{4}⋅a_{6}=2a_{5}\),设等差数列\(\{b_{n}\}\)的前\(n\)项和为\(S_{n}\),若\(b_{5}=2a_{5}\),则\(S_{9}=(\)  \()\)
              A.\(36\)
              B.\(27\)
              C.\(54\)
              D.\(45\)
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