SOLUTION: What is the sum of {{{ sum( (3 * 5^(n+1)/2^(2n)), n=8, 13) }}}?

Question 1173166: What is the sum of ?
Found 2 solutions by greenestamps, Edwin McCravy:
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

One way to get the answer would be to convert the given sum to a purely geometric series and use the formula for the sum of a finite geometric series.

Remove the factor of 3 and one of the factors of 5 in the numerator, and change in the denominator to :

=

Then

=

But the formula for the sum of a finite geometric series is awkward to use -- so you might as well simply evaluate the given sum directly, possible using an excel spreadsheet.

Answer by Edwin McCravy(20055) (Show Source): You can put this solution on YOUR website!

Wolframalpha gives the exact answer

Edwin

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