中文摘要：

The present paper offers two likely neglected applications of the classical Lagrange expansion formula.One is a unified approach to some age-old derivative identities originally due to Pfaff and Cauchy.Another is two explicit matrix inversions which may serve as common generalizations of some known inverse series relations.

英文摘要：

Abstract The present paper offers two likely neglected applications of the classical Lagrange expansion formula. One is a unified approach to some age-old derivative identities originally due to Pfaff and Cauchy. Another is two explicit matrix inversions which may serve as common generalizations of some known inverse series relations.