Use Matrices to Solve the System of Equations $\left\{ \begin{array} { l } 3 x + y - 3 z = - 5 \\x - 2 y + 4 z = 21 \\x + y + z = 9\end{array} \right.$

Essay

Use matrices to solve the system of equations. If the equations of the system are dependent, or if the system is inconsistent, so indicate. $\left\{ \begin{array} { l } 3 x + y - 3 z = - 5 \\x - 2 y + 4 z = 21 \\x + y + z = 9\end{array} \right.$