2013经济类联考数学模拟练习二（1-5）
1数列.3，12，30，60，…的一个通项公式是( )(A)
http://file.koolearn.com/2014/0118/20140118010237880.gif
(B)
http://file.koolearn.com/2014/0118/20140118010238824.gif
(C)
http://file.koolearn.com/2014/0118/20140118010238953.gif
(D)
http://file.koolearn.com/2014/0118/20140118010239989.gif
(E)以上答案均不正确
2.若数列{
http://file.koolearn.com/2014/0118/20140118010239360.gif
}的前
http://file.koolearn.com/2014/0118/20140118010240348.gif
项和
http://file.koolearn.com/2014/0118/20140118010240348.gif
，则它的通项公式是( )
(A)
http://file.koolearn.com/2014/0118/20140118010241478.gif
(B)
http://file.koolearn.com/2014/0118/20140118010241155.gif
(C)
http://file.koolearn.com/2014/0118/20140118010241621.gif
(D)
http://file.koolearn.com/2014/0118/20140118010242623.gif
(E)以上答案均不正确
3.已知{an}是等差数列，
http://file.koolearn.com/2014/0118/20140118010242447.gif
，
http://file.koolearn.com/2014/0118/20140118010243330.gif
，则
http://file.koolearn.com/2014/0118/20140118010243607.gif
等于()
(A)30 (B)27 (C)24 (D)21 (E)20
4.在等比数列{
http://file.koolearn.com/2014/0118/20140118010243291.gif
}中，已知Sn=36，S2n=54，则S3n等于
(A)63 (B)68 (C)76 (D)89 (E)86
5. 设
http://file.koolearn.com/2014/0118/20140118010244397.gif
是方程
http://file.koolearn.com/2014/0118/20140118010244718.gif
的两根，则
http://file.koolearn.com/2014/0118/20140118010245383.gif
与
http://file.koolearn.com/2014/0118/20140118010245608.gif
的等差中项A和等比中项G分别等于
(A)A=14,G=6 (B)A=14,G=
http://file.koolearn.com/2014/0118/20140118010246464.gif
http://file.koolearn.com/2014/0118/20140118010246873.gif
和数列
http://file.koolearn.com/2014/0118/20140118010246777.gif
http://file.koolearn.com/2014/0118/20140118010246873.gif
都是等差数列，则(
http://file.koolearn.com/2014/0118/20140118010247692.gif
)与(
http://file.koolearn.com/2014/0118/20140118010247943.gif
)的比值为
(A)
http://file.koolearn.com/2014/0118/20140118010247885.gif
(B)
http://file.koolearn.com/2014/0118/20140118010248672.gif
(C)
http://file.koolearn.com/2014/0118/20140118010248424.gif
(D)
http://file.koolearn.com/2014/0118/20140118010249912.gif
(E)以上答案均不正确6 (C)A=14,G=36 (D)A=-14,G=
http://file.koolearn.com/2014/0118/20140118010246464.gif
36
(E)以上答案均不正确
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