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If the closed-loop transfer function of a control system is given by \(T(s)=\dfrac{s-5}{(s+2)(s+3)}\), then it is

1. an unstable system
2. an uncontrollable system
3. a minimum phase system
4. a non-minimum phase system

Correct answer: a non-minimum phase system

Solution

A system is minimum phase only if all its zeros lie in the left half of the \(s\)-plane. Here the zero is at \(s=5\), which is in the right half-plane, so the system is non-minimum phase. Stability is determined by poles, not by this zero.

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