\[f(x) = x + |x|\]
\[f(x) = \left\{ \begin{matrix} 2x;\ \ \ x > 0 \\ 0;\ \ \ \ \ \ x \leq 0 \\ \end{matrix} \right.\ \]
\[D(f) = ( - \infty; + \infty);\ \ \]
\[E(f) = \lbrack 0;\ + \infty)\]
\[y = 0\ \ при\ x \leq 0;\]
\[y > 0\ \ при\ x > 0.\]