Given:
The system of equation is given as,
[tex]\begin{gathered} 7x-4y=28 \\ 5x-2y=17 \end{gathered}[/tex]
The objective is identify the augmented matrix for the system of equations and the solution using row operations.
Explanation:
The required augmented matrix will be,
Performing the Gauss-Jordan elimination with the following operation,
[tex]R_2=R_2-\frac{5R_1}{7}[/tex]
By applying the operation to the augmented matrix,
To find y :
On equating the second row of the matrix,
[tex]\begin{gathered} \frac{6y}{7}=-3 \\ y=\frac{-3}{\frac{6}{7}} \\ y=\frac{-3\times7}{6} \\ y=\frac{-7}{2} \end{gathered}[/tex]
To find x :
On equating the first row of the matrix,
[tex]\begin{gathered} 7x-4y=28 \\ 7x=28+4y \\ x=\frac{28+4y}{7} \end{gathered}[/tex]
Substitute the value of y in the above equation.
[tex]\begin{gathered} x=\frac{28+4(\frac{-7}{2})}{7} \\ x=\frac{28-14}{7} \\ x=\frac{14}{7} \\ x=2 \end{gathered}[/tex]
Thus the value of solutions are,
[tex]\begin{gathered} x=2 \\ y=-\frac{7}{2}=-3.5 \end{gathered}[/tex]
Hence, option (3) is the correct answer.
