Linear systems and matrices

## Linear Systems and Matrices

This section covers the fundamental relationship between systems of linear equations and their matrix representations. Understanding this equivalence is central to linear algebra, as it allows us to use matrix operations to solve linear systems efficiently.

### Key Topics
- **Equivalence**: Every linear system can be written as a vector equation and as a matrix equation `Ax = b`
- **Matrix terminology**: augmented matrix, coefficient matrix, constant vector, solution vector
- **Row reduction**: Using elementary row operations to transform augmented matrices into echelon form
- **Consistency**: Determining whether a system has zero, one, or infinitely many solutions
- **Matrix equations**: The equation `Ax = b` and its relationship to linear combinations of columns

### Core Insight
The matrix equation `Ax = b` has a solution if and only if `b` is a linear combination of the columns of `A`. This connects the algebraic problem of solving equations to the geometric concept of span.Copy