how can I please write this? I can't find the right name to find it in instructions. Thank you.
1 Answer
You can obtain what you want with the empheq
package (needless to load amsmath
nor mathtools
):
\documentclass{article}
\usepackage{empheq}
\newcommand{\MeV}{\mathrm{MeV}}
\begin{document}
\begin{empheq}[left ={\dfrac{R_\beta\cdot\rho}{\mathrm{g\cdot cm^{-2}}} =\empheqlbrace}]{alignat* = 2}
& 0{,}407\,(E_0/\MeV)^{1{,}38} & 0{,}15 < E_0 & \le 0{,}8\,\MeV \\
& 0{,}542\,(E_0/\MeV)-0{,}133 & E_0 & > 0{,}8\,\MeV
\end{empheq}
\end{document}
$abc = \left\{ \begin{aligned} d \\ e \end{aligned} \right.$
\mathrm{}
or use thesiunitx
package