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As the title describes, I tried ratio test and root test, but the answer is 1 for both.

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    For a series to converge, the sequence of terms must converge to zero. –  Oct 20 '21 at 17:09

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Hint: What is the limit of $\sqrt[n]{5}$ for $n\to\infty$?

Mirko
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You may observe that

$$5^{\frac{1}{n} }>1$$ for any positive integer $n$ and consequently $$ \sum_{n=1}^{k} 5^{\frac{1}{n} } > k$$ and consider the $\lim_{k\to \infty}$ to conclude that the series is divergent.

Infinity_hunter
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