Definition 1.4(Order of a root). Assume that f(a) and its derivatives f'(c) f(M(a)are defined and continuous on an interval about x=p. We say that f(ar)=0 has a root of order M at c =p if and only if f(p)=0,f(p),…,f-(p)=0,andf(p)≠0.(153)