ABSTRACT
As we pointed out at the beginning of Chapter 7, because only two types of roots (real and complex) can arise in the characteristic equations of linear systems of arbitrarily high order, and since real roots exhibit behavior characteristic of firstorder systems while complex root pairs behave like second-order systems, it is useful and efficient to become intimately familiar with the responses of these two classes of systems. That is, there are many practically important devices and processes that are well modeled by one of these two classes, and the more complicated systems can be considered as combinations of several first and/or second-order forms.
