91Ó°ÊÓ

To write the equations in augmented matrix place the coefficients of the equations and the constant terms into a matrix separated by a dashed line.

Here, the augmented matrices are:

$\left[\begin{array}{ccc}1& −4& 11\\ 3& 5& −1\end{array}\right]$

To make the first element in the second row a 0, multiply the first row by 3 and then subtract resultant row 1 from the row 2.

$\left[\begin{array}{ccc}1& −4& 11\\ 3& 5& −1\end{array}\right]\stackrel{R_2→R_2−3R_1}{→}\left[\begin{array}{ccc}1& −4& 11\\ 0& 17& −34\end{array}\right]$

To make the second element in the second row a 1, divide the second row by 17.

$\left[\begin{array}{ccc}1& −4& 11\\ 0& 17& −34\end{array}\right]\stackrel{\frac{1}{17}{R}_2}{→}\left[\begin{array}{ccc}1& −4& 11\\ 0& 1& −2\end{array}\right]$

Further row-reduce the augmented matrix, by making the second element in the first row a zero.

$\left[\begin{array}{ccc}1& −4& 11\\ 0& 1& −2\end{array}\right]\stackrel{R_1→R_1+4R_2}{→}\left[\begin{array}{ccc}1& 0& 3\\ 0& 1& −2\end{array}\right]$

Here, the first row will give the solution of $x$, because the coefficient of $y$ is 0 and the coefficient of $x$is 1. Similarly, the second row will give the solution of $y$, because the coefficient of $x$ is 0 and the coefficient of $y$ is 1. Therefore, the solution is $(3,−2)$.