Approximate quadratic-additive mappings in fuzzy normed spaces (Q2321418)

Summary: We examine the generalized Hyers-Ulam stability of the following functional equation: \(2 f \left(x + y + z + w\right) + f \left(- x - y + z + w\right) + f \left(- x + y - z + w\right) + f \left(- x + y + z - w\right) + f \left(x - y - z + w\right) + f \left(x - y + z - w\right) + f \left(x + y - z - w\right) - 5 f \left(x\right) - 3 f \left(- x\right) - 5 f \left(y\right) - 3 f \left(- y\right) - 5 f \left(z\right) - 3 f \left(- z\right) - 5 f \left(w\right) - 3 f \left(- w\right) = 0\), in the fuzzy normed spaces with the fixed point method.