\documentclass{article}
\usepackage{iftex}
\usepackage{ifthen}
\usepackage{epsfig}
\usepackage[utf8]{inputenc}
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% Packages requested by user
\usepackage{amsmath}

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\begin{document}
$|\nabla \phi|^2 = 1$
\pagebreak

$\nabla f\nabla \phi = 0$
\pagebreak

$|\nabla \phi|^2 = 1 $
\pagebreak

$n $
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$p $
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$n . (p - pt1) \leq 0$
\pagebreak

\[A=\begin{bmatrix}
a_{0}\quad a_{1}\quad a_{2}
\end{bmatrix}
\]
\pagebreak

$ a_{0} $
\pagebreak

$ a_{1} $
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$ a_{2} $
\pagebreak

\[A=\begin{bmatrix}
a_{00}\quad a_{01}\quad a_{02}\\
a_{10}\quad a_{11}\quad a_{12}\\
a_{20}\quad a_{21}\quad a_{22}\\
\end{bmatrix}
\]
\pagebreak

\[A=\begin{bmatrix}
a_{00}\quad a_{01}\quad a_{02}\quad a_{03}\\
a_{10}\quad a_{11}\quad a_{12}\quad a_{13}\\
a_{20}\quad a_{21}\quad a_{22}\quad a_{23}\\
a_{30}\quad a_{31}\quad a_{32}\quad a_{33}\\
\end{bmatrix}
\]
\pagebreak

$ a_{00} $
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$ a_{01} $
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$ a_{02} $
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$ a_{10} $
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$ a_{03} $
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$ a_{12} $
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$ a_{11} $
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$ a_{20} $
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$ a_{21} $
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$ a_{13} $
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$ a_{22} $
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$ a_{23} $
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$ a_{30} $
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$ a_{31} $
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$ a_{32} $
\pagebreak

$ a_{33} $
\pagebreak

\end{document}
