f(x)	f''(x)	f''(x)=0	f''(x)>0	f''(x)<0
x^3-x	6x	x=0	\langle{0,+\infty}	\langle{-\infty,0}
(2-x)^2
x^3-4x-2
\frac{x^2}{2-x^2}

f(x)	Intervali konveksnosti	Intervali konkavnosti	Točke pregiba
x^3-x
(2-x)^2
x^3-4x-2
\frac{x^2}{2-x^2}