“…After this result of Hyers, a new concept of stability for functional equations established, called today Hyers-Ulam stability, and many papers devoted to this subject (see for example [3,4,5,6,7,8,9]). In 1978, T. Rassias [10] provided a remarkable generalization with the following well-known result, which known as Hyers-Ulam-Rassias stability today.…”