优优班--学霸训练营 > 知识点挑题
全部资源
          排序:
          最新 浏览

          50条信息

            • 1. 令\(b\) \(n\)\(=\),求数列\(\{b \)\(n\)\(\}\)的前\(n\)项和\(T\) \(n\)\(.\)_______________

            • 2.

              已知数列\(\{a_{n}\}\)的通项公式是\(a_{n}=(-1)^{n-1}(n+1)\),则\(S_{2\;017}=\)________.

            • 3.

              \({{S}_{n}}\)为数列\(\left\{{a}_{n}\right\} \)的前\(n\)项和\(.\)已知\({{a}_{n}} > 0,{{a}_{n}}^{2}+2{{a}_{n}}=4{{S}_{n}}+3\),

              \((1)\)求\(\{a_{n}\}\)的通项公式
              \((2)\)设\({{b}_{n}}=\dfrac{1}{{{a}_{n}}{{a}_{n+1}}}\),求数列\(\left\{ {{b}_{n}} \right\}\)的前\(n\)项和。

            • 4.

              在数列\(\{a_{n}\}\)中,若对任意的\(n∈N^{*}\),均有\(a_{n}+a_{n+1}+a_{n+2}\)为定值,且\(a_{7}=2\),\(a_{9}=3\),\(a_{98}=4\),则数列\(\{a_{n}\}\)的前\(100\)项的和\(S_{100}= (\)    \()\)


              A.\(132\)
              B.\(299\)
              C.\(68\)
              D.\(99\)
            • 5.

              已知数列\(\{a_{n}\}\)中,\(a_{1}=1\),\(a_{n+1}=1+ \dfrac {2}{a_{n}}\),记\(b_{n}= \dfrac {a_{n}-2}{a_{n}+1}\)
              \((1)\)求证:数列\(\{b_{n}\}\)是等比数列,并求\(b_{n}\);
              \((2)\)求数列\(\{a_{n}\}\)的通项公式\(a_{n}\);
              \((3)\)记\(c_{n}=nb_{n}\),\(S_{n}=c_{1}+c_{2}+…+c_{n}\),对任意正整数\(n\),不等式\( \dfrac {m}{32}+ \dfrac {3}{2}S_{n}+n(- \dfrac {1}{2})^{n+1}- \dfrac {1}{3}(- \dfrac {1}{2})^{n} > 0\)恒成立,求最小正整数\(m\).

            • 6. 设\(f(x)\)是定义在\(R\)上的函数,对任意\(x,y\in R\),都有\(f\left( x+y \right)=f\left( x \right)+f\left( y \right)\),且\(f\left( 1 \right)=1.\)若数列\(\left\{ {{a}_{n}} \right\}\) 满足:\({{a}_{1}}=18,{{a}_{n}}-{{a}_{n-1}}=2f\left( n \right)\),\((n\geqslant 2且n∈{N}^{*}) \),则\(\dfrac{{{a}_{n}}}{n}\)的最小值是(    )
              A.\(7\)
              B.\(9\)
              C.\(\dfrac{15}{2}\)
              D.\(\dfrac{19}{2}\) 
            • 7.

              已知\({数列}\{ a_{n}\}\)的前\(n\)项\({和}{为}A_{n}\),对\({任意}n{∈}N^{{*}}{满足}\dfrac{A_{n{+}1}}{n{+}1}{-}\dfrac{A_{n}}{n}{=}\dfrac{1}{2}{,}{且}a_{1}{=}1\),\({数列}\{ b_{n}\}{满}{足}b_{n{+}2}{-}2b_{n{+}1}{+}b_{n}{=}0(n{∈}N{*}){,}b_{3}{=}5\),其前\(9\)项和为\(63{.}(1)\)求\({数列}\{ a_{n}\}{和}\{ b_{n}\}\)的通项公式\({;}(2){令}c_{n}{=}\dfrac{b_{n}}{a_{n}}{+}\dfrac{a_{n}}{b_{n}}\),\({数列}\{ c_{n}\}\)的前\(n\)项\({和}{为}T_{n}\),若对任意正整数\(n\),\({都}{有}T_{n}{\geqslant }2n{+}a\),求实数\(a\)的取值范围\({;}(3)\)将\({数列}\{ a_{n}\}{,}\{ b_{n}\}\)的项按照“当\(n\)为奇数\({时}{,}a_{n}\)放在前面;当\(n\)为偶数\({时}{,}b_{n}\)放在前面”的要求进行“交叉排列”,得到一个新的数列:\({\ \ \ \ \ \ \ \ \ \ \ \ \ \ a}_{1}{,}b_{1}{,}b_{2}{,}a_{2}{,}a_{3}{,}b_{3}{,}b_{4}{,}a_{4}{,}a_{5}{,}b_{5}{,}b_{6}{,…}\),

              求这个新数列的前\(n{项}{和}S_{n}\).
            • 8.

              已知数列\(\{\)\(a_{n}\)\(\}\)满足:\(a\)\({\,\!}_{1}\)\(+\)\(3\)\(a\)\({\,\!}_{2}\)\(+\)\(5\)\(a\)\({\,\!}_{3}\)\(+\)\(…\)\(+\)\((2\)\(n-\)\(1)·\)\(a_{n}=\)\((\)\(n-\)\(1)·3\)\({\,\!}^{n+}\)\({\,\!}^{1}\)\(+\)\(3(\)\(n\)\(∈N\)\({\,\!}^{*}\)\()\),则数列\(\{\)\(a_{n}\)\(\}\)的通项公式\(a_{n}=\)                 

            • 9.

              \((1)\)数列\(\{{a}_{n}\} \)满足\({a}_{n+1}+(-1{)}^{n}{a}_{n}=2n-1 \),则\(\{{a}_{n}\} \)的前\(12\)项和为      


              \((2)\)如图,四边形\(ABCD\)中,\(B=C=120^{\circ}\),\(AB=4\),\(BC=CD=2\),则该四边形的面积等于__________.

              \((3)\)数列\(\{{a}_{n}\} \)中,\(S_{n}\)是前\(n\)项之和,若\({a}_{1}=1,{a}_{n+1}= \dfrac{1}{3}{S}_{n},n∈{N}_{*} \),则\(a_{n}\) \(=\)___________

              \((4)\)若\(AB=2\), \(AC= \sqrt{2} BC\),则\({S}_{∆ABC} \)的最大值              .

              \((5)\)等比数列\(\{{a}_{n}\} \)中,\({a}_{1}=2 \),\(a_{8}\) \(=4\),函数\(f(x)=(x-a_{1})(x-a_{2})……(x-a_{8})\),则\(f(0)=\)_____\((\)用数字回答\()\)

              \((6)\)设\(a < 0\),若不等式\(-{\cos }^{2}x+(a-1)\cos x+{a}^{2}\geqslant 0 \)对于任意的\(x∈R\)恒成立,则\(a\)的取值范围是__________.

            • 10.

              已知等比数列\(\{ \)\(a_{n}\)\(\}\)中, \(a\)\({\,\!}_{1}=1\), \(q\)\(=2\),则 \(T_{n}\)\(= \dfrac{1}{a_{1}a_{2}}+ \dfrac{1}{a_{2}a_{3}}+…+ \dfrac{1}{a_{n}a_{n+1}}\)的结果可化为(    )

              A.\(1- \dfrac{1}{4^{n}}\)                    
              B.\(1- \dfrac{1}{2^{n}}\)
              C.\( \dfrac{2}{3}\backslashb\backslashlc\backslashく\backslashrc\backslashぐ(\backslasha\backslashvs4\backslashal\backslashco1(1\) \( \dfrac{2}{3}\left(1- \dfrac{1}{{4}^{n}}\right) \)     
              D.\( \dfrac{2}{3}\backslashb\backslashlc\backslashく\backslashrc\backslashぐ(\backslasha\backslashvs4\backslashal\backslashco1(1\)​\( \dfrac{2}{3}\left(1- \dfrac{1}{{2}^{n}}\right) \)
            0/40

            进入组卷