Hyperstability of a quadratic functional equation on abelian group and inner product spaces

Using the fixed point approach, we prove some results on hyperstability of the following quadratic functional equation f(x+y+z)+f(x−y)+f(x−z)+f(y−z)=3[f(x)+f(y)+f(z)], in the class of functions from an abelian group into a Banach space.