15. let a and b be nxn matrices over c. then (a) ab and ba always have the same set of eigenvalues (6) if ab and ba have the same set of eigenvalues then ab = b

15. Let A and B be nxn matrices over C. Then (a) AB and BA always have the same set of eigenvalues (6) If AB and BA have the same set of eigenvalues then AB = BA. (c) if A exists then AB and BA are simila (d) The rank of AB is always the same as therank 19 of BA (Net Dec. 2015)