In the feedback system shown below $$$G\left(S\right)\;=\frac1{(s^2\;+\;2s)}$$$ The step response of the closed-loop system should have minimum settling time and have no overshoot. The required value of gain k to achieve this is __________.

The number and direction of encirclements around the point −1 + j0 in the complex plane by the Nyquist plot of G(s) =$${{1 - s} \over {4 + 2s}}$$ is

The asymptotic Bode phase plot of $${\rm{G(s) = }}{k \over {\left( {s + 0.1} \right)\left( {s + 10} \right)\left( {s + {p_1}} \right)}},$$ with k and p_{1 both positive, is shown below. The value of p1 is ________}

In the feedback system shown below $${\rm{G(s) = }}{1 \over {\left( {s + 1} \right)\left( {s + 2} \right)\left( {s + 3} \right)}}$$ The positive value of 𝑘 for which the gain margin of the loop is exactly 0 dB and the phase margin of the loop is exactly zero degree is ____