ridgeboy36
What is the sum of the geometric sequence 2,8,32,... if there are 8 terms? Answers to choose from.
a)21,845
b)43,690
c)65,535
d)87,380
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geoffb
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Do you know the formula for the sum of \(n\) terms in a geometric sequence?
ridgeboy36
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no could you guide me through this whole problem
geoffb
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\[\Large{S_{n} = \frac{a_{1}(1-r^{n})}{1-r}}\]
\(a_{1}\) is your first term.
\(r\) is the ratio (what you multiply by between each term).
\(n\) is the number of terms (given as 8).
ridgeboy36
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ok
ridgeboy36
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i got 43,690 as my answer is this correct?
geoffb
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That's what I get.
ridgeboy36
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thankyou
geoffb
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No problem.