ISSN : 1226-0657
In <xref>[41]</xref>, Th.M. Rassias proved that the norm defined over a real vector space V is induced by an inner product if and only if for a fixed positive integer l <graphic></graphic> holds for all x<sub>1</sub>, ⋯ , x<sub>2l</sub> ∈ V . For the above equality, we can define the following functional equation <graphic></graphic> Using the fixed point method, we prove the Hyers-Ulam stability of the functional equation (0.1) in fuzzy Banach spaces.
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