%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-7-16 on page II-204 in "Ghostbusters\texttrademark ".
%%
%% 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{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{183.0pt}
% Shorten the vertical size of the example ...
\AtBeginDocument{%
\setlength\abovedisplayskip{.3\abovedisplayskip}%
\setlength\belowdisplayskip{.3\belowdisplayskip}%
}
%StartShownPreambleCommands
\usepackage{mathtools}
%StopShownPreambleCommands
\begin{document}
\[ \sqrt{ \frac{a+b}{x_j} } \quad
\sqrt{ \frac{a+b}{\smash{x_j}} } \quad
\sqrt{ \frac{a+b}{{}\smash{x_j}} } \quad
\sqrt{ \frac{a+b}{\smash{x_j+b}} } \]
\end{document}
