Encode and Decode Messages
Encode or decode the given message, as requested, numbering the letters of the alphabet 1 through 26 in their usual
order.
-Use the coding matrix $A = \left[ \begin{array} { l l } 2 & 1 \ 5 & 3 \end{array} \right]$ and its inverse $A ^ { - 1 } = \left[ \begin{array} { r r } 3 & - 1 \ - 5 & 2 \end{array} \right]$ to decode the cryptogram $\left[ \begin{array} { r r } 9 & 6 \ 25 & 17 \end{array} \right]$.
A) BEAD
B) CARE
C) DARE
D) CURB

Question

Quizplus · Accepted Answer

The message is encoded as follows:$$\left[ \begin{array} { r r } 9 & 6 \ 25 & 17 \end{array} ight] = \left[ \begin{array} { l l } 2 & 1 \ 5 & 3 \end{array} ight] \left[ \begin{array} { r r } 2 & 3 \ 1 & 1 \end{array} ight] = \left[ \begin{array} { r r } 5 & 11 \ 15 & 23 \end{array} ight]$$The message is decoded as follows:$$\left[ \begin{array} { r r } 5 & 11 \ 15 & 23 \end{array} ight] = \left[ \begin{array} { r r } 3 & - 1 \ - 5 & 2 \end{array} ight] \left[ \begin{array} { r r } 9 & 6 \ 25 & 17 \end{array} ight] = \left[ \begin{array} { r r } 2 & 3 \ 1 & 1 \end{array} ight]$$The message is BEAD.

Encode and Decode Messages Encode or Decode the Given Message A=[2153]A = \left[ \begin{array} { l l } 2 & 1 \\ 5 & 3 \end{array} \right]A=[25​13​]

Encode and Decode Messages
Encode or Decode the Given Message $A = \left[ \begin{array} { l l } 2 & 1 \\ 5 & 3 \end{array} \right]$