A Multidimensional Functional Equation Having Quadratic Forms as Solutions

A fixed-point approach to the stability of a functional equation on quadratic forms

“…Thereafter, many authors investigated solutions or stability of various functional equations (see [3][4][5][6][7][8][9][10][11]). …”

A Fixed Point Approach to the Stability of a Functional Equation

“…The case of approximately additive mappings was solved by D. H. Hyers [6] under the assumption that G 1 and G 2 are Banach spaces. Thereafter, many authors investigated solutions or stability of various functional equations (see [1], [2], [5], [8], [9]- [12]).…”