%% 
%%  Ein Beispiel der DANTE-Edition
%%  Mathematiksatz mit LaTeX
%%  3. Auflage
%%  Beispiel 04-04-2 auf Seite 40.
%%  Copyright (C) 2018 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% ==== 
% Show page(s) 1
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\documentclass[10pt]{screxa}
\pagestyle{empty}
\setlength\textwidth{146.40707pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\setcounter{equation}{8}
\renewcommand\theequation{4.\arabic{equation}}
\begin{document}
\begin{equation}
  \sqrt{a}\,\sqrt{T}\,\sqrt{2\alpha k_{B_1}T^i}
\end{equation}
\begin{equation}
 \sqrt{a\vphantom{k_{B_1}T^{\scriptscriptstyle i}}}\,
 \sqrt{T\vphantom{k_{B_1}T^{\scriptscriptstyle i}}}\,
 \sqrt{2\alpha k_{B_1}T^i}
\end{equation}
\end{document}