(Properties of Discrete Systems) Determine (with justification) whether the following systems are (i) memoryless, (ii) causal, (iii) invertible, (iv) stable, and (v) time invariant. For invertibility, either find an inverse system or an example of two inputs that lead to the same output. Note that y[n] denotes the system output and r[n] denotes the system input. a) y[n] = x[n]2[n – 1] x[n + 1] Sz{n-1), n<0, b) y[n] = 1 «[n +1], n>0. c) y[n] = cos(x[n])