E7.17 A control system, as shown in Figure E7.17, has a process

R(s) Ge(s) G(s) Y(s) FIGURE E7.17 Feedback system. (a) When Ge(s) = K, show that the system is always unstable by sketching the root locus. (b) When Ge(s) = K(s+2) $+20 sketch the root locus, and determine the range of K for which the system is stable. Determine the value of K and the complex roots when two roots lie on the jw-axis.