7.34 Consider the system A = 12 8 ].B= [8 ].C=[1 21. and assume that you are using feedback of the form # = -Kx + r, where r is a reference input signal. (a) Show that (A, C) is observable. (b) Show that there exists a K such that (A - BK, C) is unobservable. (c) Compute a K of the form K = [1, K2] that will make the system unob- . servable as in part. (b); that is, find K2 so that the closed-loop system is not observable. (d) Compare the open-loop transfer function with the transfer function of the closed-loop system of part (c). What is the unobservability due to