Inverse of Matrix :
     Let A be a non-singular matrix. If there exists a square matrix B such that AB = I (identity matrix) then B is called inverse of matrix A and is denoted as A^-1.
i.e AA^-1 = I
Example:

Matrix A		Matrix B	=	Identity (I)
1 3 1 1 1 2 2 3 4	x	2 9 -5 0 -2 1 -1 -3 2	=	1 0 0 0 1 0 0 0 1

In the above example Matrix A when multiplied by Matrix B gives an identity matrix. So we can call B as an inverse of A or A as an inverse of B.