Answer
The coding matrix is $\left[ \begin{matrix}
14 & 4 & -18 \\
85 & 18 & 19 \\
-33 & -7 & -9 \\
\end{matrix} \right]$.
Work Step by Step
Consider the given expression:
$ SEND\_CASH $
Where,
$ S=19,E=5,N=14,D=4,\_=0,C=3,A=1,S=19,H=8$
Using the cryptogram method we get,
$\begin{align}
& A=\left[ \begin{matrix}
1 & -1 & 0 \\
3 & 0 & 2 \\
-1 & 0 & -1 \\
\end{matrix} \right]\left[ \begin{matrix}
19 & 4 & 1 \\
5 & 0 & 19 \\
14 & 3 & 8 \\
\end{matrix} \right] \\
& =\left[ \begin{matrix}
19-5+0 & 4+0+0 & 1-19+0 \\
57+0+28 & 12+0+6 & 3+0+16 \\
-19+0-14 & -4+0-3 & -1+0-8 \\
\end{matrix} \right] \\
& =\left[ \begin{matrix}
14 & 4 & -18 \\
85 & 18 & 19 \\
-33 & -7 & -9 \\
\end{matrix} \right]
\end{align}$
Therefore, coding matrix of the expression is $\left[ \begin{matrix}
14 & 4 & -18 \\
85 & 18 & 19 \\
-33 & -7 & -9 \\
\end{matrix} \right]$.
