In this paper, the authors investigate the generalized Ulam-Hyers stability of a Leibniz type additive and quadratic functional equation ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − − + ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − + + − + − + − 3 2 3 3 = ) ( ) ( ) ( z y x f t z y x f t z f t y f t x f ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + − − + ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − + − + 3 2 3 2 z y x f z y x f in the setting of intuitionistic fuzzy normed spaces using direct and fixed point methods.

The object of this work is solubility correlation and prediction of CO2 and H2S in various aqueous alkanolamines using the electrolyte cubic square-well equation of state (eCSW EoS) (Haghtalab, A.,Mazloumi, S. H., (2010), Electrolyte Cubic Square-Well Equation of State for Computation of the Solubility CO2 and H2S in Aqueous MDEA Solutions,  Ind. Eng. Chem. Res.,49,6221-623). The eEoS systemati...

In this paper, we introduce $n$-variables mappings which are cubic in each variable. We show that such satisfy a functional equation. The main purpose is to extend the applications of fixed point method establish Hyers-Ulam stability for multi-cubic mappings. As consequence, prove equation can be hyperstable.