题型:解答题 题类:其他 难易度:较易
年份:2018
若数列\(\{a_{n}\}\)的前\(n\)项和\(S_{n}\)满足:\(S_{n}=2a_{n}-λ(λ > 0,n∈N*)\).
\((\)Ⅰ\()\)证明:数列\(\{a_{n}\}\)为等比数列,并求\(a_{n}\);
\((\)Ⅱ\()\)若\(λ=4\),\(b_{n}=\begin{cases}{a}_{n},n为奇数, \\ {\log }_{2}{a}_{n},n为偶数\end{cases} (n∈N*)\),求数列\(\{b_{n}\}\)的前\(n\)项和\(T_{n}\).
题型:解答题 题类:其他 难易度:较易
年份:2018
已知等差数列\(\{a_{n}\}\)的公差为\(2\),其前\(n\)项和\(S_{n}=pn^{2}+2n\),\(n∈N^{*}\).
\((1)\) 求实数\(p\)的值及数列\(\{a_{n}\}\)的通项公式\(;\)
\((2)\) 在等比数列\(\{b_{n}\}\)中,\(b_{3}=a_{1}\),\(b_{4}=a_{2}+4\),若\(\{b_{n}\}\)的前\(n\)项和为\(T_{n}\),求证: 数列\(\left\{ T_{n}{+}\dfrac{1}{6} \right\}\)为等比数列.
题型:解答题 题类:其他 难易度:较易
年份:2018
各项均为正数的等比数列\(\left\{ {{a}_{n}} \right\}\)中,\({{a}_{1}}=2\),且\(2{{a}_{1}}\),\({{a}_{3}}\),\(3{{a}_{2}}\)成等差数列.
\((1)\)求数列\(\left\{ {{a}_{n}} \right\}\)的通项公式;
\((2)\)设\({{b}_{n}}=\dfrac{1}{(n+2){{\log }_{2}}{{a}_{n}}}(n\in {{N}^{*}})\),记数列\(\left\{ {{b}_{n}} \right\}\)的前\(n\)项和为\({{S}_{n}}\),求证:\({{S}_{n}} < \dfrac{3}{4}\).
题型:解答题 题类:其他 难易度:较易
年份:2018
已知数列\(\left\{ {{a}_{n}} \right\}\)是等比数列,数列\(\left\{ {{b}_{n}} \right\}\)满足\({{b}_{1}}=-3,{{b}_{2}}=-6,{{a}_{n+1}}+{{b}_{n}}=n(n\in {{N}_{+}})\).
\((1)\)求\(\left\{ {{a}_{n}} \right\}\)的通项公式;
\((2)\)求数列\(\left\{ {{b}_{n}} \right\}\)的前\(n\)项和\({{S}_{n}}\).
题型:解答题 题类:其他 难易度:较易
年份:2018
.已知各项均为正数的数列\(\{\)\(a_{n}\)\(\}\)的前\(n\)项和为\(S_{n}\),满足\(a_{n+1}^{2} \)\(=\)\(2\)\(S_{n}+n+\)\(4\),\(a\)\({\,\!}_{2}\)\(-\)\(1\),\(a\)\({\,\!}_{3}\),\(a\)\({\,\!}_{7}\)恰为等比数列\(\{\)\(b_{n}\)\(\}\)的前\(3\)项.
\((1)\)求数列\(\{\)\(a_{n}\)\(\}\),\(\{\)\(b_{n}\)\(\}\)的通项公式\(;\)
\((2)\)若\(c_{n}=\)\((\)\(-\)\(1)\)\({\,\!}^{n}\)\(\log _{2}\)\(b_{n}-\)\( \dfrac{1}{{a}_{n}{a}_{n+1}} \),求数列\(\{\)\(c_{n}\)\(\}\)的前\(n\)项和\(T_{n}\).