Consider a unity feedback system where the open-loop transfer function is given by kg(s)h(-, (sa ros)- and k(s+z) is contributed by a pd controller. assume that the parameter α is determined mathematically to be 1 1) sketch the root locus for z = α = 1 . determine the range of k for which the system is stable. 2) if the actual parameter α is 1 .5 instead, sketch qualitatively the "actual" root locus 3) explain why one should not cancel an unstable open-loop pole (ie, choose z =-a ) in designing a controller