Answer:
THE CORN IS YUMMY
Step-by-step explanation:
Understanding the question:
Raj encoded a secret phrase using matrix multiplication. For that he first converted each letter in that phrase to integers using the following codes:
A=1,B=2,C=3,D=4,E=5,F=6,G=7,H=8,I=9,J=10,K=11,L=12,M=13,N=14,O=15,P=16,Q=17,R=18,S=19,T=20,U=21,V=22,W=23,X=24,Y=25,Z=26
We suppose that Raj had a matrix X formed by letters of that phrase encoded in integers/numbers. And he multiplied that matrix X with matrix C to get an encoded matrix, let us say 'encoded X'.
Where; C = ![\left[\begin{array}{ccc}2&5\\1&2\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D2%265%5C%5C1%262%5Cend%7Barray%7D%5Cright%5D)
and encoded X = ![\left[\begin{array}{ccc}85&111&135&111&95&101&153\\38&48&55&45&41&44&64\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D85%26111%26135%26111%2695%26101%26153%5C%5C38%2648%2655%2645%2641%2644%2664%5Cend%7Barray%7D%5Cright%5D)
What we need now is X.
<u>Raj got from the phrase to encoded matrix by:</u>
1. Encoding each letter into numbers and forming a matrix X.
2. Multiplying that matrix with another Matrix C to obtain the given encoded matrix.
<u>To find the secret phrase we will reverse the steps as:</u>
1. Multiplying the encoded matrix by 'Inverse of Matrix C' to get matrix X.
2. Converting the elements of X into alphabets.
Inverse of C = (Adjoint of C)/Determinant(C)
Adjoint of
= ![\left[\begin{array}{ccc}2&-5\\-1&2\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D2%26-5%5C%5C-1%262%5Cend%7Barray%7D%5Cright%5D)
Determinant of C = |C| = ad - bc = 2*2 - 5*1 = -1
Inverse of C =
/ (-1)
= ![\left[\begin{array}{ccc}-2&5\\1&-2\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-2%265%5C%5C1%26-2%5Cend%7Barray%7D%5Cright%5D)
Multiplying Inverse(C) and encoded X =
![\left[\begin{array}{ccc}85&111&135&111&95&101&153\\38&48&55&45&41&44&64\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D85%26111%26135%26111%2695%26101%26153%5C%5C38%2648%2655%2645%2641%2644%2664%5Cend%7Barray%7D%5Cright%5D)
=![\left[\begin{array}{ccc}20&8&5&3&15&18&14\\9&19&25&21&13&13&25\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D20%268%265%263%2615%2618%2614%5C%5C9%2619%2625%2621%2613%2613%2625%5Cend%7Barray%7D%5Cright%5D)
Converting these elements back to alphabets, we get:
=![\left[\begin{array}{ccc}T&H&E&C&O&R&N\\I&S&Y&U&M&M&Y\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7DT%26H%26E%26C%26O%26R%26N%5C%5CI%26S%26Y%26U%26M%26M%26Y%5Cend%7Barray%7D%5Cright%5D)
Hence, it is obvious that the secret phrase is "THECORNISYUMMY"
The location of spaces are between every word ( THE CORN IS YUMMY).