职教组卷基于海量职教高考试题库建立的在线组卷及学习系统
职教组卷
  • 题型:解答题 题类:月考试卷 难易度:中档

    在数列\(\{a _{n} \}\)中,\(a _{1} = \dfrac {1}{2},a_{n+1}-a_{n}+3a_{n+1}a_{n} =0\).
    \((1)\)证明:数列\(\{ \dfrac {1}{a_{n}}\}\)是等差数列;
    \((2)\)若\(b _{n} = \dfrac {a_{n}}{3n+2}\),求数列\(\{b _{n} \}\)的前\(n\)项和\(S _{n}\).
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