Which one of the following statements is NOT true for a square matrix 𝐴?
1
If 𝐴 is upper triangular, the eigenvalues of 𝐴 are the diagonal elements of it
2
If 𝐴 is real symmetric, the eigenvalues of 𝐴 are always real and positive
3
If 𝐴 is real, the eigenvalues of 𝐴 and 𝐴𝑇 are always the same
4
If all the principal minors of 𝐴 are positive, all the eigenvalues of 𝐴 are also positive