SOLUTION: In a sequence, what is the difference in this one? -4.5,-12.5,-62.5

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Question 552629: In a sequence, what is the difference in this one? -4.5,-12.5,-62.5
Answer by AnlytcPhil(1806) About Me  (Show Source):
You can put this solution on YOUR website!
There is no common difference, because that is not an arithmetic sequence.
It's also not a geometric sequence, because there is no common ratio.

However the nth term has this formula:

an = -21nē+55n-38.5 

And the sequence taken to a few more terms is:

-4.5,-12.5,-62.5, -154.5, -288.5, -464.5, ...


Edwin