Answer:
[tex]3x_1+5x_2=-2\\6x_1+7x_2=-1[/tex]
The augmented matrix associated to the linear system is
[tex]\left[\begin{array}{ccc}3&5&-2\\6&7&-1\end{array}\right][/tex]
Using row operations we reduce the system to echelon form:
1. We substract to the second row three times the first row and obtain the matrix
[tex]\left[\begin{array}{ccc}3&5&-2\\0&-3&3\end{array}\right][/tex] that is the echelon form of the system.
Now we use backward substitution to find the solution.
1. [tex]-3x_2=3\\x_2=-1[/tex]
2. [tex]3x_1+5x_2=-2\\3x_1+5(-1)=-2\\x_1=1[/tex]
The the unique solution is [tex](x_1,x_2)=(1,-1)[/tex]