Question

Question #47d0a

Answer 1

See below.

Explanation:

If `A` and `B` are non null hermitian then `"tr"(A^2) > 0` and `"tr"(B^2) > 0` so `"tr"(A^2) +"tr"(B^2) >0`

so if `A^2+B^2=0->A=0,B=0`