LaTeX testing

The equation \( \sum_{k} \frac{1}{k^2} = \frac{\pi^2}{6} \) should render inline, and this should render as display:

\[ \sum_k k = - \frac{1}{12} \]

Is this working?

Testing the align environment:

\[ \begin{align} \zeta(s) &= 0 \\ s &\notin \mathbb{R} \end{align} \]