Hi, 1. The problem statement, all variables and given/known data How may I determine whether a system is stable if its input is equal to its output, hence yielding a system(transfer) function equal to 1? Furthermore, could an eigenvalue zero characterize a stable system? I am attaching three examples where I am asked to determine whether the systems are stable or not. 2. Relevant equations 3. The attempt at a solution In the first two cases the system's function (transfer function) is 1, hence I am not sure how to determine stability. It seems, though, that the unit is somewhat stable whereas the exponential isn't. As for the bottom sample, do I have to perform a Laplace transform and find H(s) to determine the eigenvalues?