1.61. A system is called invertible if we can determine its input signal x uniquely by observing its output signal y. This is illustrated in Fig. 1-43. Determine if each of the following systems is invertible. If the system is invertible, give the inverse system. x y Inverse System system Fig. 1-43 (a) y(t)=2x(1) (b) y(t)=x²(1) (c) y(t)= x(r) dr 80 (d) y[n] x[k] k--x (e) y[n]-nx[n] Ans. (a) Invertible; x(t)=y(1) (b) Not invertible (c) Invertible; x(t)= dy(t) dt (d) Invertible; x[n]-y[n]-y[n-1] (e) Not invertible