SOLUTION: The first term of a geometric progression is 5 and the fifth term is 1280, the common ratio is 4 Find the eighth term of the sequence

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Question 1029022: The first term of a geometric progression is 5 and the fifth term is 1280, the common ratio is 4
Find the eighth term of the sequence
Found 2 solutions by ikleyn, MathTherapy:
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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The first term of a geometric progression is 5 and the fifth term is 1280, the common ratio is 4
Find the eighth term of the sequence
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a%5B8%5D = a%5B5%5D%2A4%5E3 = 1280*64 = 81920.


To learn more on geometric progressions, see the lesson  Geometric progressions  in this site.


Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

The first term of a geometric progression is 5 and the fifth term is 1280, the common ratio is 4
Find the eighth term of the sequence
The 1st term and common ratio (r) are enough to determine the 8th term. No other term, not even the 5th, is needed.



Specific term of a GP: a%5Bn%5D+=+a%5B1%5Dr%5E%28n+-+1%29

a%5B8%5D+=+5%284%29%5E%288+-+1%29 ------- Substituting 8 for n, 5 for a%5B1%5D, the 1st term, and 4 for r, the common ratio

a%5B8%5D+=+5%284%29%5E7

8th term or