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        1. 已知等差數(shù)列{}中共有18項(xiàng),其中奇數(shù)項(xiàng)之和為11,偶數(shù)項(xiàng)之和為29,則其公差為(     )

          A.4B.3C.2D.1

          C

          解析考點(diǎn):等差數(shù)列的性質(zhì).
          分析:由題意可得奇數(shù)項(xiàng)有9項(xiàng),偶數(shù)項(xiàng)有9項(xiàng),設(shè)公差為d,則由 9d="29-11" 即可求得公差d的值.
          解:由題意可得奇數(shù)項(xiàng)有9項(xiàng),偶數(shù)項(xiàng)有9項(xiàng),設(shè)公差為d,則 9d=29-11=18,
          ∴d=2,
          故選C.

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