This is a question on a quiz, so I'm not looking for the answer, just a pointer in the right direction.
I have the following matrix:
I computed the characteristic polynomial and got the following eigenvalues:
(i-4) and (i+4)
Unfortunately, the matrix that I got by multiplying (i-4) by identity(3) and subtracting the original matrix reduces to identity(3) according to my calculator. (i+4) does the same.
Can anyone help, or do I need to provide more information?