2-1 Show that trace of AB = trace of BA

> restart;

> A:=Matrix([[a,b],[c,d]]);

> B:=Matrix([[p,q],[r,s]]);

> A.B;

> B.A;

> trace(A.B);

> ?trace

> ?Trace;

> with(linalg);

Warning, the protected names norm and trace have been redefined and unprotected

> trace(A.B);

> trace(B.A);

> trace(A.B-B.A);