TIME INVARIANCE
A system is defined as "time invariant" when its output is not an explicit function of time. To figure out whether a system is time invairant, we need to look for a value t outside of the normal x(t) or y(t). If it does not contain such a value t outside of the x(t), then it is time invariant. For instance, consider the following systems: SYSTEMS: A.) h1(t) = 2x1(3t) + 5 B.) h2(t) = 6t*x2(3t) + 5 System A does not contain a "t" outside of the x1(3t). Therefore, we can call it time invariant. However, system B does contain a "t" outside of the x2(3t). Thus, system B is not time invariant.
