A、<img width='48' height='25' src='/s/tiw/p3/UpLoadImage/2016-09-19/7be54fb9-1f46-4b9a-8bda-2709c6173ca7.png'>
B、<img width='40' height='25' src='/s/tiw/p3/UpLoadImage/2016-09-19/f42c24d3-1ca8-4337-aea0-d01260e6ec43.png'>
C、<img width='17' height='21' src='/s/tiw/p3/UpLoadImage/2016-09-19/92d4f547-10a6-4f20-97b3-2b95ce2a10b6.png'>
D、<img width='47' height='25' src='/s/tiw/p3/UpLoadImage/2016-09-19/f99c847c-2697-454d-bad0-d321082883c2.png'>
E、3<sup>7</sup>
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正确答案
试题解析
The given sequence is a geometric sequence whose nth term is
![](/s/tiw/p3/UpLoadImage/2016-09-19/945193b9-b2c9-43d3-9ac8-e9152e168aca.png)
.
![](/s/tiw/p3/UpLoadImage/2016-09-19/b5b5e89f-3a0d-4c8d-8beb-f6699bb15cb7.png)
,
![](/s/tiw/p3/UpLoadImage/2016-09-19/0a4aa61f-b0e5-4ba1-af03-d5362a3ed2a8.png)
=9(3) =27,
![](/s/tiw/p3/UpLoadImage/2016-09-19/372e9a96-618f-43e7-a7ef-edaf17bd3e81.png)
. The sixth term is, therefore,
![](/s/tiw/p3/UpLoadImage/2016-09-19/7be54fb9-1f46-4b9a-8bda-2709c6173ca7.png)
.