P9.21 Consider a unity feedback system with the loop transfer function

(a) Sketch the Bode plot for K = 4. Determine

(b) the gain margin,

(c) the value of K required to provide a gain margin equal to 12 dB, and

(d) the value of K to yield a steady-state error of 25% of the magnitude A for the ramp input r1t2 = At, t 7 0. Can this gain be utilized and achieve acceptable performance?