Дана функция f(x) =x^2; x<=-1; f(x)=x+5; -1<x<4; f(x)=3; x>=4. Найдите: f (4).

\[f(x) = \left\{ \begin{matrix} x^{2};\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x \leq - 1 \\ x + 5;\ \ \ \ - 1 < x < 4 \\ 3;\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x \geq 4 \\ \end{matrix} \right.\ \]

\[f(4) = 3\]