2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/159697We show that for fixed $A,B$, hermitian nonnegative definite matrices, and fixed $k$ the coefficients of the $t^k$ in the polynomial $\tr (A+tB)^m$ is positive if $\tr AB >0$ and $m>N(A,B,k)$.6 pagesMathematical Physicstext