Fuzzy Stability of Jensen-Type Quadratic Functional Equations

We prove the generalized Hyers-Ulam stability of the following quadratic functional equations 2f((x + y)/2) + 2f((x - y)/2) = f(x) + f(y) and f(ax + ay) + (ax - ay) = 2a(2)f(x) = 2a(2)f(y) in fuzzy Banach spaces for a nonzero real number a with a not equal +/- 1/2. Copyright (C) 2009 Sun-Young Jang et al.Dr. Sun-Young Jang was supported by the Research Fund of University of Ulsan in 2008, and Dr. Choonkil Park was supported by National Research Foundation of Korea (NRF-2009-0070788)