A unity feedback system has a loop transfer function

L(s) = KG(s) = K(s + 1) s(s + 6s+18) (a) Sketch the root locus for K > 0. (b) Find the roots when K = 10 and 20. (c) Compute the rise time, percent overshoot, and settling time (with a 2% criterion) of the system for a unit step input when K = 10 and 20.