Answer:
[tex]\left[\left.\begin{matrix}1 & 0 & 0\\ 0 & 6 & 0\\ 0 & 0 & 7\end{matrix}\right|\begin{matrix}7\\ 5\\ 5\end{matrix}\right][/tex]
Step-by-step explanation:
The given augmented matrix is
[tex]\left[\left.\begin{matrix}3 & 0 & 0\\ 0 & 6 & 0\\ 0 & 0 & 7\end{matrix}\right|\begin{matrix}21\\ 5\\ 5\end{matrix}\right][/tex]
Here, we need to perform the row operation [tex]\dfrac{1}{3}R_1[/tex] and replace [tex]R_1[/tex] in the above matrix.
So, divide each element of [tex]R_1[/tex] in the given matrix and other elements remain same.
[tex]\left[\left.\begin{matrix}\dfrac{3}{3} & \dfrac{0}{3} & \dfrac{0}{3}\\ 0 & 6 & 0\\ 0 & 0 & 7\end{matrix}\right|\begin{matrix}\dfrac{21}{3}\\ 5\\ 5\end{matrix}\right][/tex]
[tex]\left[\left.\begin{matrix}1 & 0 & 0\\ 0 & 6 & 0\\ 0 & 0 & 7\end{matrix}\right|\begin{matrix}7\\ 5\\ 5\end{matrix}\right][/tex]
Therefore, the required matrix is [tex]\left[\left.\begin{matrix}1 & 0 & 0\\ 0 & 6 & 0\\ 0 & 0 & 7\end{matrix}\right|\begin{matrix}7\\ 5\\ 5\end{matrix}\right][/tex].
