7. For the unity-feedback system shown in the figure below, where K(s + 10)(s + 20)
a. Sketch the root locus, b. Find the range of gain, K, that makes the system stable. c. Find the value of K that yields a damping ratio of 0.707 for the system’s closed-loop dominant poles. d. Find the value of K that yields closed-loop critically damped dominant poles.