SOLUTION: The sum of how many terms of the series 3,-6,12, ....will be 513?
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Question 891783: The sum of how many terms of the series 3,-6,12, ....will be 513?
Answer by josgarithmetic(39618) (Show Source): You can put this solution on YOUR website!
That looks like geometric sequence, .
The general sequence's term is and n would be the index of the term.
You can think of the sequence this way:
3, 3(-2)^1, 3(-2)^2, 3(-2)^3, 3(-2)^4,....3(-2)^n
This way showing the sequence uses indexing from 0 to n-1.
Sum of the first n terms is .
For reference, other than a good college algebra book, you can see http://en.wikipedia.org/wiki/Geometric_series.
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