Find $\det(A - nI_n)$, where $A$ is an $n \times n$ matrix whose entries are all 1, and $I_n$ is the $n \times n$. identity matrix.
I have no clue how to approach this. If $A$ is an $n \times n$ matrix whose entries are all $1$, then the determinant is $0$?
What does $nI_n$ mean? The identity matrix multiplied by the number of rows/columns? (I realize that they are equal because it is a square matrix)