Use Matrices to Solve the System of Equations $\left\{ \begin{array} { l } x + y + z = 6 \\x + 3 y + z = 8 \\x + y + 3 z = 12\end{array} \right.$

Multiple Choice

Use matrices to solve the system of equations. $\left\{ \begin{array} { l } x + y + z = 6 \\x + 3 y + z = 8 \\x + y + 3 z = 12\end{array} \right.$

A) $( 1,2,3 )$
B) $( - 2 , - 1 , - 3 )$
C) $( 2,1,3 )$
D) no solution
E) infinitely many solutions