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PS4

by winter » Sun Jul 18, 2010 2:33 pm
In the arithmetic sequence t1, t2, t3, .... tn, .... t1 = 23 and tn = (tn-1) - 3 for each n>1. What is the value of n when tn = -4?

1) -1
2) 7
3) 10
4) 14
5)20

QA is 10
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by Haaress » Sun Jul 18, 2010 2:58 pm
Ooops! Please move this question to PS.

Anywayz, tn = (tn-1) - 3 and n = 1 , tn = 23.

For such a small series , we can count. Thus, the series is 23, 20, 17, 14, 11, 8,5,2,-1,-4 , basically subtracting a -3 from the previous term. So -4 is the 10th term .
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by reply2spg » Mon Jul 19, 2010 7:02 am
ans is C. Please move this question to PS section
winter wrote:In the arithmetic sequence t1, t2, t3, .... tn, .... t1 = 23 and tn = (tn-1) - 3 for each n>1. What is the value of n when tn = -4?

1) -1
2) 7
3) 10
4) 14
5)20

QA is 10
Sudhanshu
(have lot of things to learn from all of you)
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