Stability of a mixed type cubic–quartic functional equation in non-Archimedean spaces

In this paper, we prove the Hyers–Ulam–Rassias stability of the mixed type cubic–quartic functional equation f ( x + 2 y ) + f ( x − 2 y ) = 4 ( f ( x + y ) + f ( x − y ) ) − 24 f ( y ) − 6 f ( x ) + 3 f ( 2 y ) in non-Archimedean normed spaces.