Respuesta1
He aquí una propuesta.
\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}
\edef\lstadd{{0,16,-12}}
\edef\lstsub{{-4,0,6}}
\matrix[matrix of math nodes,nodes={text width=1.5em}] (mat)
{
0 & 2 & 1 & 0 & 2 \\
3 & -1 & 2 & 3 & -1\\
4 & -4 & 1 & 4 & -4\\
};
\foreach \X [evaluate=\X as \Y using {int(\X+2)}]in {1,2,3}
{\pgfmathtruncatemacro{\mylabel}{\lstadd[\X-1]}
\draw[purple,-latex,thick] (mat-1-\X.north west) -- (mat-3-\Y.south east)
node[pos=1.1]{\mylabel};
\pgfmathtruncatemacro{\mylabel}{\lstsub[\X-1]}
\draw[purple,-latex,thick] (mat-3-\X.south west) -- (mat-1-\Y.north east)
node[pos=1.1]{\mylabel};
}
\end{tikzpicture}
\end{document}
O
\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}
\edef\lstadd{{0,16,-12}}
\edef\lstsub{{-4,0,6}}
\matrix[matrix of math nodes,nodes={text width=1.5em}] (mat)
{
0 & 2 & 1 & 0 & 2 \\
3 & -1 & 2 & 3 & -1\\
4 & -4 & 1 & 4 & -4\\
};
\foreach \X [evaluate=\X as \Y using {int(\X+2)}]in {1,2,3}
{\pgfmathtruncatemacro{\mylabel}{\lstadd[\X-1]}
\draw[purple,-latex,thick] (mat-1-\X.north west) -- (mat-3-\Y.south east)
node[pos=1.1] (LL-\X) {\mylabel};
\pgfmathtruncatemacro{\mylabel}{\lstsub[\X-1]}
\draw[purple,-latex,thick] (mat-3-\X.south west) -- (mat-1-\Y.north east)
node[pos=1.1] (LU-\X) {\mylabel};
}
\draw[line width=1mm,purple,latex-,shorten >=1cm,shorten <=1cm]
(LU-3.east) -- ++ (3,0) node[right] {Subtract these products};
\draw[line width=1mm,purple,latex-,shorten >=1cm,shorten <=1cm]
(LL-3.east-|LU-3.east) -- ++ (3,0) node[right] {Add these products};
\end{tikzpicture}
\end{document}