优优班--学霸训练营 > 知识点挑题
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            • 1.
              如果等差数列\(\{a_{n}\}\)中,\(a_{3}+a_{4}+a_{5}=12\),那么\(a_{1}+a_{2}+…+a_{7}=(\)  \()\)
              A.\(14\)
              B.\(21\)
              C.\(28\)
              D.\(35\)
            • 2.
              等差数列\(\{a_{n}\}\)的前\(m\)项和为\(30\),前\(2m\)项和为\(100\),则它的前\(3m\)项和为\((\)  \()\)
              A.\(130\)
              B.\(170\)
              C.\(210\)
              D.\(260\)
            • 3.
              已知等差数列\(\{a_{n}\}\)的公差为\(2\),若\(a_{1}\),\(a_{3}\),\(a_{4}\)成等比数列,则\(a_{2}\)等于\((\)  \()\)
              A.\(-4\)
              B.\(-6\)
              C.\(-8\)
              D.\(-10\)
            • 4.
              已知数列\(\{a_{n}\}\)的前\(n\)项和\(S_{n}\),\(a_{1}=1\),\(a_{n+1}=a_{n}+ \dfrac {1}{2}(n∈N*)\),则\( \dfrac {S_{2017}}{2017}\)的值为\((\)  \()\)
              A.\(503\)
              B.\(504\)
              C.\(505\)
              D.\(506\)
            • 5.

              已知等比数列\(\{a_{n}\}\)的公比\(q > 1\),\(a_{1}=1\),且\(2a_{2}\),\(a_{4}\),\(3a_{3}\)成等差数列.

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

              \((2)\)记\(b_{n}=2na_{n}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}\).

            • 6.

              等差数列\(\left\{ {{a}_{n}} \right\}\)中,\({{a}_{5}}=1,{{a}_{1}}+{{a}_{7}}+{{a}_{10}}={{a}_{4}}+{{a}_{6}}\),则\({{S}_{10}}=(\)   \()\)

              A.\(-\dfrac{2}{3}\)
              B.\(\dfrac{8}{3}\)
              C.\(5\)
              D.\(\dfrac{25}{3}\) 
            • 7.

              已知数列\(\{a\)\({\,\!}_{n}\)\(\}\)是等差数列,\({{b}_{n}}=\dfrac{{{a}_{1}}+{{a}_{2}}+\ldots +{{a}_{n}}}{n}\)\((n=1,2,3,…)\).

              证明:数列\(\{b_{n}\}\)是等差数列.

            • 8.
              若等差数列\(\{a_{n}\}\)中有\(a_{2}+a_{4024}=4\),则\(a_{2013}=(\)  \()\)
              A.\(2\)
              B.\(4\)
              C.\(3\)
              D.\(6\)
            • 9.

              设等差数列\(\{a_{n}\}\)的前\(n\)项的和为\(S_{n}\),且\(S_{13}=52\),则\(a_{4}+a_{8}+a_{9}=(\)    \()\)

              A.\(8\)
              B.\(12\)
              C.\(16\)
              D.\(20\)
            • 10.

              已知数列\(\{{{a}_{n}}\}\)中,\({{a}_{1}}=1\),\(a_{n+1}^{{}}=a_{n}^{{}}+3\),则\({{a}_{6}}=(\)    \()\)

              A.\(16\)
              B.\(13\)
              C.\(10\)
              D.\(7\)
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