**
Dimensions
** -
The number of rows and the number of columns in a matrix. For example,
a 3×4-dimensional matrix has 3 rows and 4 columns.

**
Elementary Row Operations
** -
There are three elementary row operations:

- Multiplying a row by a constant.
- Switching two rows.
- Adding a constant times a row to another row.

**
Identity Matrix
** -
The matrix

Which, when multiplied by any matrix, does not change the matrix. In
other words, any matrix multiplied by

*I* is equal to itself.

**
Matrix
** -
A way of representing data in a rectangular array.

**
Reduced Row-Echelon Form
** -
The form of a matrix in which the first

*m*×*m* entries form the
identity matrix:

**
Row Reduction
** -
The process through which a matrix is converted to reduced row-echelon
form, using elementary row operations.

**
Scalar
** -
A single constant, variable, or expression.