Identity matrix  Matrices
Identity matrix
Lessons
Notes:
An identity matrix is an $n$ by $n$ matrix (written as
$I_n$) where all the entries that is diagonal from the top
left to the bottom right are all 1’s, and the rest of the entries are 0. For example,
are all identity matrices.

a)
The Identity Matrix

b)
Multiplicative Inverses


2.
Matrix Operation with the Identity Matrix
You are given that and . Perform the following matrix operations: 
3.
Multiplicative Inverses
Are the following matrices multiplicative inverses of each other?