Fuzzy stability of Jensen-type quadratic functional equations (Q1030630)

Summary: 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 \(a\neq \pm 1/2\).