#uw/notes #uw/class/math208 - - - - Not all systems of linear equations will be in echelon form and easily solvable - There are three **elementary operations** that can be used to create a new system that is equivalent to the old one - Interchange the position of two equations - Multiply an equation by a nonzero constant - Add a multiple of one equation to another - $\sim$ is used to indicate the transformation between equivalent linear systems - matricies can be used to simplify when working with systems of linear equations - matricies with all constant terms of a linear system of equations are called a **augmented matrix** - $$\begin{align*} a_{11}x_{1} + a_{12}x_{2} + a_{13} \end{align*}$$