## College Algebra (6th Edition)

$I_{n}$ is an $n\times n$ matrix that has 1s down the main diagonal from upper left to lower right and 0s elsewhere.
The multiplicative identity matrix $I_{n}$ is an $n\times n$ matrix such that $AI_{n}=I_{n}A=A$ for all n$\times$n matrices. $I_{n}$ is an $n\times n$ matrix that has 1s down the main diagonal from upper left to lower right and 0s elsewhere.