Squared norm of matrix equal to squared norm of its transpose
Hint: note that $$ \|Mx\|^2 = (Mx)^T(Mx) = x^T(M^TM)x $$
Show that the non zero eigenvalues of $AB$ and $BA$ are the same. (In this case $A=M,B=M^T$).
Squared norm of matrix equal to squared norm of its transpose
Hint: note that $$ \|Mx\|^2 = (Mx)^T(Mx) = x^T(M^TM)x $$
Show that the non zero eigenvalues of $AB$ and $BA$ are the same. (In this case $A=M,B=M^T$).