Determine if each of the following systems is invertible. If it is, construct the inverse system. If it is not, find two input signals to the system that have the same output.
(a) y(t) = -x(t - 4)
(b) y(t) = cos(x(t)) * x[n - 11]
(c) y[n] = nx[n]
(d) y[n] = 0, n <= -1
(e) y[n] = x[0], n >= 0
(f) V(f) = X(20), n = 0
(g) y[n] = x[1 - n]
(h) y(t) = ∫x(t) dt
(i) V(f) = X(-20), n = 0
(j) v[n] = x[n+1]