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\begin{document}

\begin{mybox}
\eq{
\left(\frac{a^2}{a}\right)\\
\left(\frac{a^2}{a}\right)
}
\eq{
\left(\frac{a^2}{a}\right)\\
\left(\frac{a^2}{a}\right)
}
\eq{
\stackrel ! =
\\\hspace{20cm} \left(\frac{a^2}{a}\right)
\\e^{F_0}
\\x
\\\left(\frac{a^2}{a}\right)
}
\end{mybox}
abc
\eq{
\frac{e^x}{e^x+1}
}
\section{abc}
\begin{mybox}
\eq{
x\\
x
}
\eq{
\left(\frac{a^2}{a}\right)\\
\left(\frac{a^2}{a}\right)
}
\eq{
\left(\frac{a^2}{a}\right)\\
\left(\frac{a^2}{a}\right)
}
\end{mybox}
\begin{mybox}
\eq{
  \int_{-\infty}^a\left(\frac{a^2}{a}\right)
\\ \frac{\sqrt{F}}{a}\frac{a}{\sqrt{F}}_{\big\vert}
\\ \frac{\sqrt{F}}{\sqrt{F}}
\\ \frac{\sqrt{F}}{a}\left(\frac{F}{a}\right)
}
\eq{
\frac{\frac{\beta}{\sqrt{F}}}{\frac{\beta}{\sqrt{F}}}
}
\eq{
x
}
\end{mybox}

\end{document}