The open-loop transfer function of a unity feedback control

The open-loop transfer function of a unity feedback control system is
G(s) = K(s + 2)
(s + 1)(s - 7)

For K > 6, the stability characteristic of the openloop and closed-loop configurations of the system are respectively

1. stable and unstable
2. stable and stable
3. unstable and stable
4. unstable and unstable

In open-loop system, there is a pole in RHP. So system is unstable.
In closed loop system

T(s) =	K(s + 2)
	s² + (K - 6)s + 2K - 7

For stability K > 6, 2K – 7 > 0
⇒ K > 6
So for K > 6, system is stable.

G(s) =	K(s + 2)
	(s + 1)(s - 7)