Find x1 and x2

[alg]

Find [tex]x_{1 } and x_{2 }[/tex]

[Guest]

Expand using matrix multiplication:
[tex]\begin{bmatrix}
1 & -1 \\
1 & -2\end{bmatrix}
\begin{bmatrix}
x_{1 }\\
x_{2 }
\end{bmatrix}
=
\begin{bmatrix}
x_{1 } -x_{2 }\\
x_{1 } -2x_{2 }
\end{bmatrix}[/tex]
so
[tex]\begin{bmatrix}
5\\
7
\end{bmatrix}
=
\begin{bmatrix}
x_{1 } -x_{2 }\\
x_{1 } -2x_{2 }
\end{bmatrix}[/tex]
Then you can solve the simultaneous equations
[tex]5 = x_{1 } - x_{2 }\\
7 = x_{1 } - 2x_{2 }[/tex]
To find [tex]x_{1 }[/tex] and [tex]x_{2 }[/tex]