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:填空题 题类:期末考试 难易度:较易

    等差数列\(\{a _{n} \}\)的前\(n\)项和为\(S _{n}\),\(a _{3} =3\),\(S _{4} =10\),则\(a _{n} =\)______;\( \dfrac {1}{S_{1}} + \dfrac {1}{S_{2}} +…+ \dfrac {1}{S_{2020}} =\)______.
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