A MathJax Test

Math between \( \) is shown inline: \(\sum_{k=1}^n k = \frac{n(n+1)}{2}\).

Math between \[ \] is shown by itself:

\[ \sum_{k=1}^n k = \frac{n(n+1)}{2} \]

Math between \begin{align} \end{align} is aligned:

\begin{align} a &= b + c + d\\ &= d + c + b\\ \end{align}