If characteristic equation of a closed-loop system is1 +

If characteristic equation of a closed-loop system is
1 + K = 0
s(s + 1)(s + 2)

then centroid at the asymptotes in root-locus will be

σ_A =	∑ real parts of pole - ∑ real parts of zero
	number of poles - number of zero

=	0 - 1 - 2 - 0	= -1
	3 - 1

1 +	K	= 0
	s(s + 1)(s + 2)