The closed-loop transfer function of a control system is

The closed-loop transfer function of a control system is given by
C(s) = 2(s - 1)
R(s) (s + 2)(s + 1)

For a unit step input the output is

1. – 3e ^{– 2t} + 4e ^{– t} – 1
2. – 3e ^{– 2t} – 4e ^{– t} + 1
3. zero
4. infinity

	C(s)	=	2(s - 1)	, R(s) =	1
	R(s)		(s + 2)(s + 1)		s

Hence , C(s) =	2(s - 1)
	s(s + 1)(s + 2)

=	K₁	+	K₂	+	K₃
	s		s + 1		s + 2

Hence , C(s) =	-1	+	4	-	3
	s		s + 1		s + 2

⇒ c(t) = [– 1 + 4e^{– t} – 3e^{– 2t}]