Question

What is a unit matrix?

Answer 1

The unit matrix is every `n`x `n` square matrix made up of all zeros except for the elements of the main diagonal that are all ones.
For example:

It is indicated as `I_n` where `n` representes the size of the unit matrix.

The unity matrix in linear algebra works a little bit like the number 1 in normal algebra so that if you multiply a matrix by the unit matrix you get the same initial matrix!