Academic Editor: Patricia J. Y. Wong
Copyright © 2010 Won-Gil Park and Jae-Hyeong Bae. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We prove the Hyers-Ulam stability of a 2-dimensional quadratic functional equation in a class of vector variable functions in Banach modules over a unital -algebra.