) A discrete-time system has the following poles, zp, and zeros, z., poles: zp = {0.475/3 +0.475j, o +0.7;} zeros: zz = {+j, -B}, where a and B are two real numbers. a Indicate the ranges of a and B, for which the system is stable or marginally stable, and justify your answer. (11) Carefully plot the poles and zeros in the z-plane when a = -0.7 and B = 1.2. (iii) Sketch an approximation of the magnitude frequency response of the system of Al(f)(ii), indicating any normalised frequencies of significance.