%%
%% The LaTeX Companion, 3ed
%%
%% Example 12-3-22 on page II-246 in "Support for Times math".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{207.0pt}
%StartShownPreambleCommands
\usepackage{newtxmath}
%StopShownPreambleCommands

\begin{document}
\[  xjfA \to  x_j \neq y_f
                  \neq z_A  \]
\end{document}