infinite series - 7

logistic_guy

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\(\displaystyle \textcolor{indigo}{\bold{Solve.}}\)

\(\displaystyle \sum_{k=0}^{\infty}\frac{5^k}{3}\)
 
Let us compute a few terms.

\(\displaystyle \sum_{k=0}^{\infty}\frac{5^k}{3} = \frac{1}{3} + \frac{5}{3} + \frac{5^2}{3} + \cdots\)

Well this is a geometric series.

\(\displaystyle \sum_{k=0}^{\infty}\frac{5^k}{3} = \lim_{k\rightarrow \infty}\frac{1}{3}\left(\frac{1 - 5^k}{1 - 5}\right) \longrightarrow\) \(\displaystyle \textcolor{blue}{\text{this series diverges since} \ 5 > 1}\).
 
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