1. A linear equation is an equation that has one or more variables with degree one. Matrix multiplication and Gaussian elimination are two methods to solve linear equations using matrices.
2. A system of linear equations can be represented by an augmented matrix, with each row representing one equation and each column representing a variable or constant term.
3. A linear system is homogeneous if multiplying the input by a constant also multiplies the output by the same constant. It is additive if the output of multiple inputs summed is equal to the sum of the individual outputs.