Prefer a chat interface with context about you and your work?
Stability and hyperstability of a quadratic functional equation and a characterization of inner product spaces
Abstract We have proved theHyers-Ulam stability and the hyperstability of the quadratic functional equation f (x + y + z) + f (x + y − z) + f (x − y + z) + f (−x + y + z) = 4[f (x) + f (y) + f (z)] …