For a system, we learn the following three properties: (1) Memoryless, (2) Time-variant, (3) Linear, and (4) Casual. Determine which of these properties hold and which do not hold for each of the following continuous-time systems.
a) y(t)= dx(t)/dt
b) y(t) = x(t/3)
c) y(t) = [cos(3t)]x(t)