the fixed point alternative methods are implemented to givehyers-ulam stability for the quintic functional equation $ f(x+3y)- 5f(x+2y) + 10 f(x+y)- 10f(x)+ 5f(x-y) - f(x-2y) = 120f(y)$ and thesextic functional equation $f(x+3y) - 6f(x+2y) + 15 f(x+y)- 20f(x)+15f(x-y) - 6f(x-2y)+f(x-3y) = 720f(y)$ in the setting ofintuitionistic fuzzy normed spaces (ifn-spaces). this methodintroduces a met...
