數(shù)列練習(xí)含答案

1、1數(shù)學(xué)（必修數(shù)學(xué)（必修5）第二章：數(shù)列）第二章：數(shù)列[基礎(chǔ)訓(xùn)練A組]一、選擇題1在數(shù)列553421853211x中，x等于（）A11B12C13D142等差數(shù)列92739963741前則數(shù)列中nnaaaaaaaa??????項(xiàng)的和9S等于（）A66B99C144D2973等比數(shù)列??na中243952??aa則??na的前4項(xiàng)和為（）A81B120C168D192412?與12?，兩數(shù)的等比中項(xiàng)是（）A1B1?C1?D215已知一等比數(shù)

2、列的前三項(xiàng)依次為3322??xxx，那么2113?是此數(shù)列的第（）項(xiàng)A2B4C6D86在公比為整數(shù)的等比數(shù)列??na中，如果12183241????aaaa那么該數(shù)列的前8項(xiàng)之和為（）A513B512C510D8225二、填空題1等差數(shù)列??na中33952??aa則??na的公差為______________。2數(shù)列na是等差數(shù)列，47a?，則7s?_________3兩個(gè)等差數(shù)列????nnba327......2121??????

3、???nnbbbaaann則55ba=___________.4在等比數(shù)列??na中若75393??aa則10a=___________.34.C2(21)(21)11xx??????5.B2(33)(22)1414xxxxxxx????????????或而133313134()422222nxqnx??????????6.C332112131(1)18()12222qaqaqqqqqq?????????或而89182(12)22225

4、1012qZqaS?????????二、填空題1.85233985252aad???????2.4971747()7492Saaa????3.12651955199“55199199()2792652929312()2aaaaaaSbbbbSbb?????????????4.3375?633109255755qqaaq???????5.2?471102aaaa???6112n?111111...242422333log33...3log

5、(333)log(3)nnn????????????????211[1()]111122...11222212nnn?????????三、解答題1.解：設(shè)四數(shù)為33adadadad????，則2242640aad???即1333222ad???或，當(dāng)32d?時(shí)，四數(shù)為25811當(dāng)32d??時(shí)，四數(shù)為118522.解：181920212220125572.80.4aaaaaaaadd?????????201283.13.26.3aad??