test

\[E=mc^2 \]

\begin{align}
tanh(x)& = sinh(x)/cosh(x)& = \frac{e^x - e^{-x}}{ex + e^{-x}} & = \frac{e^{2x} - 1}{e^{2x} + 1} & = \frac{1 - e^{-2x}}{1 + e^{-2x}}
\end{align}