“…This theorem was later extended for all p = 1 and this result of Rassias lead mathematicians working in stability of functional equations to establish what is known today as Hyers-Ulam-Rassias stability or Cauchy-Rassias stability as well as to introduce new definitions of stability concepts. During the last three decades, several stability problems of a large variety of functional equations have been extensively studied and generalized by a number of authors [2], [5], [12], [6], [7], [10], [17], [11], [18], [19], and [20]. In particular, Cho and et al [4] introduced the quintic functional equation…”