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.
              已知等差数列\(\{a_{n}\}\),公差\(d > 0\),前\(n\)项和为\(S_{n}\),且满足\(a_{2}a_{3}=45\),\(a_{1}+a_{4}=14\).
              \((1)\)求数列\(\{a_{n}\}\)的通项公式及前\(n\)项和\(S_{n}\);
              \((2)\)设\(b_{n}= \dfrac {S_{n}}{n- \dfrac {1}{2}}\),
              \(①\)求证\(\{b_{n}\}\)是等差数列.
              \(②\)求数列\(\{ \dfrac {1}{b_{n}\cdot b_{n+1}}\}\)的前\(n\)项和\(T_{n}\).
              \(③\)求\( \lim\limits_{n→∞}T_{n}\).
            • 2.
              已知数列\(\{a_{n}\}\)的前项和为\(S_{n}\),\(S_{n}=1+ta_{n}(t\neq 1\)且\(t\neq 0\),\(n∈N*)\)
              \((1)\)求证:数列\(\{a_{n}\}\)是等比数列
              \((2)\)若\( \lim\limits_{n→∞}S_{n}=1\),求实数\(t\)的取值范围.
            0/40

            进入组卷