SOLUTION: Find the partial sum Sn of the geometric sequence that satisfies the given conditions. a = 7, r = 2, n = 5

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Question 1158774: Find the partial sum Sn of the geometric sequence that satisfies the given conditions.
a = 7, r = 2, n = 5
Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
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Use the formula for the sum of a geometric progression.


If  a, ar, ar%5E2, . . . , ar%5E%28n-1%29%5D  is the geometric progression with the first term  " a ",   the common ratio  " r ",  and the number of terms  " n "

then the sum of its first  n  terms is

      S%5Bn%5D = a+%2B+ar+%2B+ar%5E2+%2B+ellipsis+%2B+ar%5E%28n-1%29 = %28ar%5En+-+a%29%2F%28r-1%29.

Or,  which is the same

      S%5Bn%5D = a%2A%28%28r%5En+-+1%29%2F%28r-1%29%29.


Substitute the given data into the formula and calculate.

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On geometric progressions,  see introductory lessons
    - Geometric progressions
    - The proofs of the formulas for geometric progressions
    - Problems on geometric progressions
    - Word problems on geometric progressions
in this site.

Also,  you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic
"Geometric progressions".

Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.