Consider the unity-feedback system whose open-loop transfer function is G(s) = K s(s+ 1)(s + 4) a. (5 points) What is the magnitude expression of the open-loop transfer function? b. (5 points) What is the phase angle expression of the open loop transfer function? c. (5 points) Estimate the gain and phase crossover frequencies. d. (5 points) Estimate the gain and phase margins. e. (5 points) Using MATLAB, provide a Bode plot with all gain and phase margins and crossover frequencies labeled. The Bode plots for G(s) (gain-adjusted, but uncompensated system) is shown as: Magnitude (dB) Phase (deg) 30 20 10 0 -10 -20 -30 -40 -90 -135 -180 -225 -270 10-1 10 Frequency (rad/sec) 10