Answer
Diverges
Work Step by Step
Let us consider an alternating series $\Sigma_{k=1}^\infty(-1)^k a_k$ that can be convergent , when it satisfy the following two conditions such as: 1) The magnitude of terms must form a non-increasing sequence.
2) $\lim\limits_{k \to \infty} a_k=0$
Here, in the problem we are given that $a_k=\dfrac{1}{5^k}$
a) In the given sequence, $a_k=1+\dfrac{1}{k}$ , and $a_{k+1}=1+\dfrac{1}{k+1}$ and $\dfrac{1}{k+1} \leq 1+\dfrac{1}{k}$
This implies that $a_{k+1} \lt a_k$ and $a_{k+1} \gt 0$ , so the terms are a non-increasing sequence.
b) $\lim\limits_{k \to \infty} a_k=\lim\limits_{k \to \infty} (1+ \dfrac{1}{k})=1\ne 0$
This implies that the given series diverges.
