Let x(t) be a signal with x(t) = 0 for t < 3. For each signal given below, determine the values of t for which it is guaranteed to be zero,
(a) x(1 - t)
(b) x(1 - t) + x(2 - t) (c) x(1 - t)x(2 - t) (d) x(3t)
(e) x(t/3)