The basic point of this part is to formulate systems of linear equations in terms of matrices. We can then view them as analogous to an equation like 7_x_ = 5.
In order to use them in systems of equations we will need to learn the algebra of matrices; in particular, how to multiply them and how to find their inverses.
Geometrically, a linear equation in x, y and z is the equation of a plane. Solving a system of linear equations is equivalent to finding the intersection of the corresponding planes.