Hi I am new here and also new to QM. I have encountered a problem about postulate 2 which is the superposition principle. Basically I understand the concept. However, when it comes to real question, I get stuck and can't proceed. Could anyone enlightens me how to get started with the problem below? Question: A psi(x) = [psi(x)]^2 Is A a linear operator? Is A a Hermitian?