Solution 3.8.7.1 In part (a) the output is C = AG+ B In the block diagram of part (b) wehave C = (A+ BX)G = AG+ BXG: This says that X = G ;1 : The waytothink about is to note that in part (a) B does not go through G.Inpart (b) it does so wehave condition B bymultiplying by the inverse of G. 1