If AAA and BBB are n×nn \times nn×n matrices and AB=BAAB = BAAB=BA, which of the following is true?
AAA and BBB must have the same eigenvalues.
AAA and BBB must share at least one eigenvector.
AAA and BBB must be diagonal matrices.
det(A+B)=det(A)+det(B)\det(A+B) = \det(A) + \det(B)det(A+B)=det(A)+det(B)