Matrix

*This is a rectangular array of real or complex numbers, symbols, expressions arranged in rows and columns. 

Entry/Entries
*aij
*The individual items in a matrix, wherein (i) is the row and (j) is the column. 

Rows
*Horizontal lines. 

Columns
*Vertical lines.

 Real Matrix
*A entry consisting of real numbers. 

Square Matrix
*A matrix with the same number of rows and columns. 

Sizes of Matrices:
*A matrix with m rows and n columns (an m x n matrix) is said to be of size m x n.  

*One common use of matrix is to represent systems of linear equations. 

Augmented Matrix
*The matrix derived from the coefficients and constant terms of a system of linear equations. 

Coefficient Matrix
*The matrix containing only the coefficients of the system.