Re: Sum of a geometric series
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Find the sum (s) of a geometric series for which A1=48, An=3, and r=-1/2
Now, the formula is s = A1/1-r, so 48/1.5 = 32 is what I get.
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The formula you site is true if you go to infinity, that is you keep summing terms till infinity
48 - 24 + 12 - 6 + 3 - 3/2 + 3/4 - 3/8 + 3/16 - ...
But the problem tells you An = 3, hence you stop the sum at 3. The formula is different in that case. Either way, to sum five terms, there's no need of a formula.
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