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Urgent! ! ! Xicheng district senior high school mathematics compulsory five unit examination questions: series of answers
Unit test two series

1-8CDBADBAC

9 13

10 3

1 1 15

12 16; 255

13 -9

14 145

15 n(n-9) or -n(n-9)

16 8/3[ 1-(- 1/2)^n]

17 8 10 12 or 17 10 3.

18 n(2n+ 1)

19 b 1=3, geometric series with common ratio of 2.

(2) An = (3n-1) 2 n-2

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