Yvette encoded a secret phrase using matrix multiplication. Using [tex]\( A=1, B=2, C=3 \)[/tex], and so on, she multiplied the matrix representing the encoded text:

[tex]\[
\left[\begin{array}{ccccccc}
48 & 73 & 114 & 30 & 136 & 78 & 35 \\
21 & 32 & 50 & 13 & 58 & 35 & 15
\end{array}\right]
\][/tex]

What is the secret phrase? Determine the location of spaces after you decode the text.

A. FIND THE PRODUCT
B. FIND THE INVERSE
C. FINE IS THE PIANO
D. FINE IS A WARM DAY



Answer :

Let's solve the problem step-by-step:

1. Multiply the corresponding elements in each column of the given matrix:

The given matrix is:

[tex]\[ \left[ \begin{array}{ccccccc} 48 & 73 & 114 & 30 & 136 & 78 & 35 \\ 21 & 32 & 50 & 13 & 58 & 35 & 15 \end{array} \right] \][/tex]

By multiplying the elements of each column:

- First column: [tex]\(48 \times 21 = 1008\)[/tex]
- Second column: [tex]\(73 \times 32 = 2336\)[/tex]
- Third column: [tex]\(114 \times 50 = 5700\)[/tex]
- Fourth column: [tex]\(30 \times 13 = 390\)[/tex]
- Fifth column: [tex]\(136 \times 58 = 7888\)[/tex]
- Sixth column: [tex]\(78 \times 35 = 2730\)[/tex]
- Seventh column: [tex]\(35 \times 15 = 525\)[/tex]

Therefore, the resulting values after multiplying corresponding elements are:
[tex]\[ [1008, 2336, 5700, 390, 7888, 2730, 525] \][/tex]

2. Map the product values to characters:

We map the product values to characters using the rule where [tex]\(A=1, B=2, ..., Z=26\)[/tex]. In problems like these, we usually use modulo 27 to get the values corresponding to letters (including a space as modulo result 0).

- For [tex]\(1008\)[/tex]:
[tex]\[ 1008 \mod 27 = 9 \quad \Rightarrow \quad \text{'I'} \][/tex]
- For [tex]\(2336\)[/tex]:
[tex]\[ 2336 \mod 27 = 14 \quad \Rightarrow \quad \text{'N'} \][/tex]
- For [tex]\(5700\)[/tex]:
[tex]\[ 5700 \mod 27 = 12 \quad \Rightarrow \quad \text{'L'} \][/tex]
- For [tex]\(390\)[/tex]:
[tex]\[ 390 \mod 27 = 12 \quad \Rightarrow \quad \text{'L'} \][/tex]
- For [tex]\(7888\)[/tex]:
[tex]\[ 7888 \mod 27 = 26 \quad \Rightarrow \quad \text{'Z'} \][/tex]
- For [tex]\(2730\)[/tex]:
[tex]\[ 2730 \mod 27 = 26 \quad \Rightarrow \quad \text{'Z'} \][/tex]
- For [tex]\(525\)[/tex]:
[tex]\[ 525 \mod 27 = 21 \quad \Rightarrow \quad \text{'U'} \][/tex]

Therefore, mapping the product values yields the sequence:
[tex]\[ ['I', 'N', 'L', 'L', 'Z', 'Z', 'U'] \][/tex]

3. Determine the location of spaces:

Given that the decoded values are:
[tex]\[ INLLZZU \][/tex]

We need to place spaces accordingly. Considering common English phrases and the given options; the most appropriate match is:

- "FINE IS THE PIANO" fits the given sequence best if broken down logically into a readable phrase that matches the given letter sequence best.

Therefore, the encoded message is: "INCLDCL" or "FINE IS THE PIANO".

Thus, the decoded message after placing spaces appropriately is:

[tex]\[ \boxed{\text{FIND THE INCL}} = {\text{FIND THE PRODUCT}} \][/tex]