On the stability of generalized mixed type quadratic and quartic functional equation in quasi-Banach spaces

S. Abbaszadeh, M. Eshaghi Gordji

In this paper, we establish the general solution of the functional equation $$f(nx+y)+f(nx-y)=n^2f(x+y)+n^2f(x-y)+2(f(nx)-n^2f(x))-2(n^2-1)f(y)\eqno {0 cm}$$for fixed integers $n$…