优优班--学霸训练营 > 知识点挑题
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            • 1. 已知数列\(\{a\)\({\,\!}_{n}\)\(\}\)满足\(a\)\({\,\!}_{n+1}\)\(-a\)\({\,\!}_{n}\)\(=2[f(n+1)-f(n)](n∈N\)\({\,\!}^{*}\)\().\)
              \((1)\)若\(a\)\({\,\!}_{1}\)\(=1\),\(f(x)=3x+5\),求数列\(\{a\)\({\,\!}_{n}\)\(\}\)的通项公式;

              \((2)\)若\(a\)\({\,\!}_{1}\)\(=6\),\(f(x)=2\)\({\,\!}^{x}\)且\(λa\)\({\,\!}_{n}\)\( > 2\)\({\,\!}^{n}\)\(+n+2λ\)对一切\(n∈N\)\({\,\!}^{*}\)恒成立,求实数\(λ\)的取值范围.

            • 2.

              已知\({{S}_{n}}\)为正项数列\({ }\!\!\{\!\!{ }{{{a}}_{n}}{ }\!\!\}\!\!{ }\)的前\(n\)项和,且满足\(2{{S}_{n}}={{a}_{n}}^{2}+{{a}_{n}}\left( n\in {{N}^{*}} \right)\).

              \((1)\)求出\({{a}_{1}},{{a}_{2}},{{a}_{3}},{{a}_{4}}\),

              \((2)\)猜想\({ }\!\!\{\!\!{ }{{{a}}_{n}}{ }\!\!\}\!\!{ }\)的通项公式并给出证明.

            • 3.

              已知正项数列\(\left\{ {{a}_{n}} \right\}\)中,\({{a}_{1}}=1,{{a}_{2}}=2,2a_{n}^{2}=a_{n-1}^{2}+a_{n+1}^{2}\left( n\geqslant 2 \right),{{b}_{n}}=\dfrac{1}{{{a}_{n}}+{{a}_{n+1}}}\),记数列\(\left\{ {{b}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),则\({{S}_{33}}\)的值是\((\)   \()\)

              A.\(\sqrt{99}\)
              B.\(\sqrt{33}\)
              C.\(4\sqrt{2}\)
              D.\(3\)
            • 4.

              已知等比数列\(\left\{ {{a}_{n}} \right\}\)的公比是\(q\),首项\({{a}_{1}} < 0\),前\(n\)项和为\({{S}_{n}}\),设\({{a}_{1}},{{a}_{4}},{{a}_{3}}-{{a}_{1}}\)成等差数列,若\({{S}_{k}} > \dfrac{31}{16}{{a}_{1}}\),则正整数\(k\)的最大值是\((\)  \()\)

              A.\(4\)
              B.\(5\)
              C.\(14\)
              D.\(15\)
            • 5. 设等差数列\(\{\)\(a_{n}\)\(\}\)的前\(n\)项和为\(S_{n}\),若\(S_{m}\)\({\,\!}_{-1}=-2\),\(S_{m}\)\(=0\),\(S_{m}\)\({\,\!}_{+1}=3\),则\(m\)\(=(\)  \()\).
              A.\(3\)
              B.\(4\)
              C.\(5\)
              D.\(6\)
            • 6.

              在\(\Delta ABC\)中,\(A,B,C\)的对边分别为\(a,b,c\)且\(a{\cos }C,b{\cos }B,c{\cos }A\)成等差数列.

              \((1)\)求\(B\)的值;

              \((2)\)求\(2{si}{{{n}}^{2}}A+{\cos }\left( A-C \right)\)的范围.

            • 7.

              已知正项数列\(\{a_{n}\}\)的前\(n\)项和为\(S_{n}\),对任意\(n∈N^{*}\),点\(\left( \left. a_{n},S_{n} \right. \right)\)都在函数\(f\left( \left. x \right. \right)= \dfrac{1}{2}x^{2}+ \dfrac{1}{2}x\)的图象上.

              \((1)\)求数列\(\{a_{n}\}\)的首项\(a_{1}\)和通项公式\(a_{n}\);

              \((2)\)若数列\(\left\{ \left. b_{n} \right. \right\}\)满足\(\log _{2}b_{n}=n+\log _{2}\left( \left. 2a_{n}-1 \right. \right)\left( \left. n∈N^{*} \right. \right)\),求数列\(\left\{ \left. b_{n} \right. \right\}\)的前\(n\)项和\(T_{n}\);

              \((3)\)已知数列\(\left\{ \left. c_{n} \right. \right\}\)满足\(c_{n}= \dfrac{4n-6}{T_{n}-6}- \dfrac{1}{a_{n}a_{n+1}}\left( \left. n∈N^{*} \right. \right).\)若对任意\(n∈N^{*}\),存在\(x_{0}∈\left[ \left. - \dfrac{1}{2}, \dfrac{1}{2} \right. \right]\),使得\(c_{1}+c_{2}+…+c_{n}\leqslant f(x)-a\)成立,求实数\(a\)的取值范围.

            • 8.

              平面直角坐标系\(xoy\)中,已知点\(\left(n,{a}_{n}\right) n∈{N}^{*} \)在函数\(y={a}^{x}\left(a\geqslant 2,a∈N\right) \)的图像上,点\(\left(n,{b}_{n}\right) (n∈{N}^{*} )\)在直线\(y=\left(a+1\right)x+b b∈R \)上\(.\)

              \((1)\)若点\(\left(1,{a}_{1}\right) \)与点\(\left(1,{b}_{1}\right) \)重合,且\({a}_{2} < {b}_{2} \),求数列\(\left\{{b}_{n}\right\} \)的通项公式;

              \((2)\)证明:当\(a=2\)时,数列\(\left\{{a}_{n}\right\} \)中任意三项都不能构成等差数列;

              \((3)\)当\(b=1\)时,记\(A=\left\{ \left.x \right|x={a}_{n},n∈{N}^{*}\right\} \),\(B=\left\{ \left.x \right|x={b}_{n},n∈{N}^{*}\right\} \),设\(C=A∩B \),将集合\(C\)的元素按从小到大的顺序排列组成数列\(\left\{{c}_{n}\right\} \),写出数列\(\left\{{c}_{n}\right\} \)的通项公式\({c}_{n} \).
            • 9. 在各项均为正数的等比数列\(\{a_{n}\}\)中,\(a_{1}=2\),且\(2a_{1}\),\(a_{3}\),\(3a_{2}\)成等差数列.
              \((\)Ⅰ\()\) 求等比数列\(\{a_{n}\}\)的通项公式;
              \((\)Ⅱ\()\) 若数列\(\{b_{n}\}\)满足\(b_{n}=11-2\log _{2}a_{n}\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}\)的最大值.
            • 10.

              已知数列\(\{ a_{n}\}\)中,\(a_{1}{=}2\),\(a_{n}{=}2{-}\dfrac{1}{a_{n{-}1}}(n{\geqslant }2{,}n{∈}\mathrm{N}^{{*}}) .\)设\(b_{n}{=}\dfrac{1}{a_{n}{-}1}(n{∈}\mathrm{N}^{{*}})\).

              \((1)\)求证:数列\(\{ b_{n}\}\)是等差数列;

              \((2)\)设数列\(\{\dfrac{1}{b_{n}b_{n{+}2}}\}\)的前\(n\)项和为\(T_{n}\),若\(T_{n}{\leqslant }\dfrac{m}{12}(m{∈}\mathrm{N}^{\mathrm{{*}}})\)对任意\(n{∈}\mathrm{N}^{{*}}\)恒成立,求\(m\)的最小值.

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