Hyers-Ulam stability results for a functional inequality of \((s, t)\)-type in Banach spaces (Q2138094)

Summary: We introduce an additive \(\left( s , t\right)\)-functional inequality where \(s\) and \(t\) are nonzero complex numbers with \(\sqrt{ 2}\left| s\right|+\left| t\right|<1\). Using the direct method and the fixed point method, we give the Hyers-Ulam stability of such functional inequality in Banach spaces.