The systems below have input x(t) or x[n] and output y(t) or y[n]. For each system, determine whether the system is invertible. If the system is invertible, indicate how you can recover x(t) (or x[n]) from y(t) (or y[n]). (a) y[n] = x[n+4] If invertible, specify how x[n] can be recovered from y[n]. (b) y(t)=x^(t) If invertible, specify how x(t) can be recovered from y(t)