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:选择题 题类:期中考试 难易度:中档

    已知等比数列\(\{ a_{n}\}\)中,\(a_{2}{=}2\),又\(a_{2}{,}a_{3}{+}1{,}a_{4}\)成等差数列,数列\(\{ b_{n}\}\)的前\(n\)项和为\(S_{n}\),且\(\dfrac{1}{S_{n}}{=}\dfrac{1}{n}{-}\dfrac{1}{n{+}1}\),则\(a_{8}{+}b_{8}{=}({  })\)

    A. \(311\)                     B. \(272\)                      C. \(144\)                      D. \(80\)
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