Terms and definitions:

Matrix: A rectangular arrangement of mn elements in the form of an ordered set of m rows, each row consisting of an ordered set of n elements is called m x n matrix.

Types of Matrices

• Row matrix: A matrix having only one row

• Column matrix: A matrix having only one column

• Zero/Null matrix: Matrix whose all elements are zero

• Square matrix: A matrix whose number of rows and columns are equal

• Diagonal matrix: A square matrix whose non-diagonal elements are always zero

• Scalar matrix: A Diagonal matrix in which all the diagonals are equal and non-diagonal elements are zero

• Identity/Unit matrix: A scalar matrix where all diagonal elements are 1 and non-diagonal elements are zero

• Triangular matrix: A square matrix where all elements towards either side (upper or lower) are zero

Practice Questions:

Question: Let A = [ 3 7 -1 || 0 2 5 ] and B = [ 7 9 0 || 3 -5 6]. Find the sum of (2,2) entries of A and B. Answer: - 3

Question: Find the value of x - y + z if [ x+y+z || x+z || y+z ] = [ 9 5 7 ]. Answer: 1