https://www.chegg.com/homework-help/questions-and-answers/3-consider-following-closed-loop-system-r-s-r-s-s-1-s-5--draw-real-axis-portion-root-locus-q42260545

https://www.chegg.com/homework-help/questions-and-answers/4-consider-following-closed-loop-system-ys--find-loop-transfer-function-f-s-k-b-plot-root--q42258502