ANSWER:
[tex]6\cdot R_1+R_2=\begin{bmatrix}{0} & 39 & {23} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix}[/tex]
STEP-BY-STEP EXPLANATION:
We have the following matrix:
[tex]\begin{bmatrix}{1} & 5 & {4} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix}=\begin{cases}R_1 \\ R_2 \\ R_3\end{cases}[/tex]
Now, we apply the following changes
[tex]\begin{gathered} 6\cdot R_1+R_2 \\ 6\cdot R_1=\begin{bmatrix}{6\cdot1} & 6\cdot5 & 6\cdot{4} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix}=\begin{bmatrix}{6} & 30 & {24} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix} \\ 6\cdot R_1+R_2=\begin{bmatrix}{6+(-6)} & 30+9 & {24+(-1)} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix}=\begin{bmatrix}{0} & 39 & {23} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix} \\ 6\cdot R_1+R_2=\begin{bmatrix}{0} & 39 & {23} \\ {-6} & {9} & {-1} \\ {3} & {7} & {0}\end{bmatrix} \end{gathered}[/tex]
