Danke schon mal

\documentclass{article} \usepackage{amsmath} \begin{document} \[Pr(x_{i}\mid \chi_{i})= \begin{cases} \frac{1}{2}+\frac{1}{2}\tanh \frac{\chi_i}{2} &,x_i=+1;\\ \frac{1}{2}-\frac{1}{2}\tanh \frac{\chi_i}{2} &,x_i=-1; \end{cases}\] \begin{equation} Formel + Nummer = Formelnummer :) \end{equation} \end{document}
\documentclass{article} \usepackage{amsmath} \begin{document} \begin{equation} Pr(x_{i}\mid \chi_{i})= \begin{cases} \frac{1}{2}+\frac{1}{2}\tanh \frac{\chi_i}{2} &,x_i=+1;\\ \frac{1}{2}-\frac{1}{2}\tanh \frac{\chi_i}{2} &,x_i=-1; \end{cases} \end{equation} \begin{equation} Formel + Nummer = Formelnummer \end{equation} \end{document}