My Math Forum Shifted Geometric Sequences

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 October 3rd, 2016, 01:58 PM #1 Newbie   Joined: Oct 2016 From: United States of America Posts: 7 Thanks: 0 Shifted Geometric Sequences I am currently taking Advanced Algebra and we have a test with a couple of questions about Shifted Geometric Sequences. I understand how to find a specific term in a sequence (The 10th term, etc.) when I am given an equation such as Un=Un-1(1+0.6)+30 with the first term, and I can identify a shifted geometric sequence with no issues. However, my problem is finding the equation when I am given the terms. Example?: 0, 20, 38, 44, 68 Help?? Last edited by Imnomermaid112; October 3rd, 2016 at 02:05 PM.
October 3rd, 2016, 03:25 PM   #2
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Quote:
 Example?: 0, 20, 38, 44, 68
That is not a geometric sequence, because there is no common ratio.

Are you sure the 4th term is 44 and not 54?

Last edited by skipjack; October 6th, 2016 at 05:56 AM.

 October 5th, 2016, 01:44 PM #3 Newbie   Joined: Oct 2016 From: United States of America Posts: 7 Thanks: 0 Yes, that's what I meant, thank you for pointing out my error. Anyways, I figured out how to do it, so I won't need any further assistance. Thank you!
October 6th, 2016, 06:02 AM   #4
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Quote:
 Originally Posted by skeeter Are you sure the 4th term is 44 and not 54?
That suggests that 0, 20, 38, 54, 68 was intended, with the first differences being an arithmetic progression, so it wouldn't be a shifted geometric sequence.

October 6th, 2016, 06:13 AM   #5
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Quote:
 Originally Posted by skipjack That suggests that 0, 20, 38, 54, 68 was intended, with the first differences being an arithmetic progression, so it wouldn't be a shifted geometric sequence.
I thought I said that ...

I just asked about the 44 term to try and make some mathematical sense from the sequence the OP listed.

 Tags geometric, sequences, shifted

### find the common ratio of a geometric progression whose sixth term is 54 and whose third term is -2

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