#### KillaKem

##### Junior Member level 2

The characteristic equation of the system is 1 + KGH(s) = 1 + K(s)G(s).

Now when finding the root locus you find the poles and zeros at K=0 ( Open loop poles and zeros ) by finding the poles and zeros of G(s).This is what I really don't understand, if K= 0 then the characteristic equation should be 1 + 0 * G(s) = 0 meaning that they don't exist, the poles should also be undefined.Why does it seem like we are actually taking K to be 1?