We have a P $($proportional$)$ controller for the negative feedback system below. Find the range of K that maintains a stable system

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$(1)/($s$^3+10$s$^2+10$s$)1$ k

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a$)$ u$($t$)(10$pts$)$

b$)$ a ramp function $($shown below; notice the amplitude of the ramp!$).(10$pts$)$

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r$($t$)$

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c$)$ t$2$u$($t$)(10$pts$)$

$(20$ pts$.)$ We have a P $($proportional$)$ controller for the negative feedback system below. Find the range of K that maintains a stable system.