Explore a diverse range of topics and get answers from knowledgeable individuals on IDNLearn.com. Get the information you need from our community of experts who provide accurate and comprehensive answers to all your questions.

Kamal wrote the augmented matrix below to represent a system of equations:

[tex]\[
\left[\begin{array}{ccc|c}
1 & 0 & 1 & -1 \\
1 & 3 & -1 & -9 \\
3 & 2 & 0 & -2
\end{array}\right]
\][/tex]

Which matrix results from the operation [tex]\(-3 R_2 \leftrightarrow R_2\)[/tex]?

A. [tex]\(\left[\begin{array}{ccc|c}
1 & 0 & 1 & -1 \\
-3 & -9 & 3 & 27 \\
3 & 2 & 0 & -2
\end{array}\right]\)[/tex]

B. [tex]\(\left[\begin{array}{ccc|c}
1 & 0 & 1 & -1 \\
-3 & -3 & -3 & -3 \\
3 & 2 & 0 & -2
\end{array}\right]\)[/tex]


Sagot :

To determine which matrix results from the given operation [tex]\(-3 R_2 \leftrightarrow R_2\)[/tex] on the original augmented matrix, we need to carefully apply the operation to the second row of the initial matrix.

Here is the original matrix:
[tex]\[ \left[\begin{array}{ccc|c} 1 & 0 & 1 & -1 \\ 1 & 3 & -1 & -9 \\ 3 & 2 & 0 & -2 \end{array}\right] \][/tex]

The operation [tex]\(-3 R_2 \leftrightarrow R_2\)[/tex] indicates that each element in the second row should be multiplied by [tex]\(-3\)[/tex].

Let's perform this operation on the second row step by step:

- For the first element of the second row: [tex]\(1 \times -3 = -3\)[/tex]
- For the second element of the second row: [tex]\(3 \times -3 = -9\)[/tex]
- For the third element of the second row: [tex]\(-1 \times -3 = 3\)[/tex]
- For the fourth element of the second row (the augmented part): [tex]\(-9 \times -3 = 27\)[/tex]

So the new second row after applying [tex]\(-3 R_2 \leftrightarrow R_2\)[/tex] will be:
[tex]\[ [-3, -9, 3, 27] \][/tex]

Thus, the resulting matrix will be:
[tex]\[ \left[\begin{array}{ccc|c} 1 & 0 & 1 & -1 \\ -3 & -9 & 3 & 27 \\ 3 & 2 & 0 & -2 \end{array}\right] \][/tex]

Therefore, the correct matrix resulting from the operation [tex]\(-3 R_2 \leftrightarrow R_2\)[/tex] is:
[tex]\[ \left[\begin{array}{ccc|c} 1 & 0 & 1 & -1 \\ -3 & -9 & 3 & 27 \\ 3 & 2 & 0 & -2 \end{array}\right] \][/tex]

This corresponds to the first given option:
[tex]\[ \left[\begin{array}{ccc|c} 1 & 0 & 1 & -1 \\ -3 & -9 & 3 & 27 \\ 3 & 2 & 0 & -2 \end{array}\right] \][/tex]