Multiplication by a matrix can be used to encode messages (and multiplication by its inverse can be used to decode messages). Given the code a b c d
And the code matrix , use matrix A to encode the message "The die is cast."
A)
B)
C)
D)
E)

Question

Multiplication by a matrix can be used to encode messages (and multiplication by its inverse can be used to decode messages). Given the code a b c d 
And the code matrix  , use matrix A to encode the message "The die is cast."
A) ​ 
B) ​ 
C) ​ 
D) ​ 
E) ​

Quizplus · Accepted Answer

To encode the message, we first need to convert the letters to numbers using their alphabetical order:

T  h  e     d  i  e     i  s     c  a  s  t
20 8 5     4 9 5     9 19    3 1 19 20

We then group these numbers into a matrix with size 4x3:

20 8 5
4  9 5
9  19 3
1  19 20

To encode this matrix, we multiply it with the given code matrix A:

11ea984b_ae97_46b3_9029_cf55b7e89fb9_TB4005_11

And we get:

11ea984b_ae97_6dc5_9029_514a9d79d957_TB4005_11

This corresponds to choice B.

Multiplication by a Matrix Can Be Used to Encode Messages