Determine a correct sequence of row operations to change the matrix

[tex]\[
\left[\begin{array}{ccc} 5 & 1 & 2 \\ 2 & -2 & 6 \\ 7 & 0 & 1 \end{array}\right]
\][/tex]

to the matrix

[tex]\[
\left[\begin{array}{ccc} 1 & -1 & 3 \\ 0 & 6 & -13 \\ 7 & 0 & 1 \end{array}\right].
\][/tex]

[tex]\[
\begin{array}{c}
\square \\
\frac{1}{2} R_2 \\
-5 R_2 + R_1 \text{ replaces } R_1 \\
\text{switch } R_2 \text{ and } R_1 \\
3 R_1 \\
-3 R_2 + R_3 \text{ replaces } R_3 \\
\square \\
\square \\
\square \\
\end{array}
\][/tex]



Answer :

To transform the matrix [tex]\(\left[\begin{array}{ccc}5 & 1 & 2 \\ 2 & -2 & 6 \\ 7 & 0 & 1\end{array}\right]\)[/tex] to the matrix [tex]\(\left[\begin{array}{ccc}1 & -1 & 3 \\ 0 & 6 & -13 \\ 7 & 0 & 1\end{array}\right]\)[/tex], we need to perform a sequence of row operations. Here are the steps:

1. Multiply the second row by 2:
[tex]\(2 R_2 \rightarrow R_2\)[/tex]
2. Use the new second row to update the first row:
[tex]\(-5 R_2 + R_1 \rightarrow R_1\)[/tex]

Here is the detailed step-by-step process:

Start with the matrix:
[tex]\[ \left[\begin{array}{ccc} 5 & 1 & 2 \\ 2 & -2 & 6 \\ 7 & 0 & 1 \end{array}\right] \][/tex]

1. Multiply the second row by 2 to get:
[tex]\[ 2 \cdot \left[\begin{array}{ccc} 2 & -2 & 6 \end{array}\right] = \left[\begin{array}{ccc} 4 & -4 & 12 \end{array}\right] \][/tex]
Now the matrix looks like this:
[tex]\[ \left[\begin{array}{ccc} 5 & 1 & 2 \\ 4 & -4 & 12 \\ 7 & 0 & 1 \end{array}\right] \][/tex]

2. Update the first row by adding -5 times the new second row to the first row:
[tex]\[ \left(5, 1, 2 \right) + (-5 \cdot \left(4, -4, 12\right)) = \left(5, 1, 2\right) + \left(-20, 20, -60\right) = \left[-15, 21, -58\right] \][/tex]
Now the matrix looks like this:
[tex]\[ \left[\begin{array}{ccc} -15 & 21 & -58 \\ 4 & -4 & 12 \\ 7 & 0 & 1 \end{array}\right] \][/tex]

Thus, the transformation sequence is:
1. [tex]\(2 R_2 \rightarrow R_2\)[/tex]
2. [tex]\(-5 R_2 + R_1 \rightarrow R_1\)[/tex]

So, the correct sequence of row operations is:

- [tex]\(2 R_2\)[/tex]
- [tex]\(-5 R_2 + R_1\)[/tex]

Fill in the boxes accordingly:

- [tex]\(2 R_2\)[/tex]
- [tex]\(-5 R_2 + R_1\)[/tex] replaces [tex]\(R_1\)[/tex]