calculus - Convergence or divergence for infinite series $sum_{n=1}^{infty} frac{(-1)^5(-5)^n}{n5^n}$

Can someone please explain why this diverges or converges and explain which test they used? For some reason my mind isn't working today and I am getting really frustrated.

$\displaystyle\sum_{n=1}^{\infty} \dfrac{((-1)^5)((-5)^n)}{n5^n}$

Answer

Take out 1 negative sign from $(-5)^n$, and you will see that the series can be written as $\displaystyle\sum_{n=1}^{\infty}\dfrac{(-1)^n}{n}$. This is (conditionally) convergent by alternating series test.