1. For each of the following systems, determine with justification whether the system is i memoryless ii causal iii stable iv linear v time-invarient (a) y[n] = 1 k-2 x[n-k] dx(t) (b) y(t) dt (c) y[n] = nx[-n] +5 (d) y(t) = [1 + cos(25nt)]x(t)