Prove Convergence using direct comparison test: $\sum^{\infty}_{k=0} a_k$ converges absolutely $\Rightarrow \sum^{\infty}_{k=0} a_k^2$ converges
$\sum a_{n}$ is convergent, $\sum a_{n}^2$ is divergent. Prove $\sum a_{n}$ is conditionally convergent.