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}