\[\boxed{\text{18\ (18).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[Найдем\ значения\ функции\ \]
\[на\ концах\ заданного\ отрезка.\]
\[\textbf{а)}\ f(x) = 2x - 1 \Longrightarrow линейная\ \]
\[функция;\]
\[1 \leq x \leq 4:\ \ \]
\[f(1) = 2 \cdot 1 - 1 = 1;\ \ \]
\[f(4) = 2 \cdot 4 - 1 = 7;\]
\[E(f) = \lbrack 1;7\rbrack.\]
\[\textbf{б)}\ g(x) = - 3x + 8 \Longrightarrow линейная\ \]
\[функция;\]
\[- 2 \leq x \leq 5:\text{\ \ }\]
\[g( - 2) = - 3 \cdot ( - 2) + 8 = 14;\ \ \]
\[g(5) = - 3 \cdot 5 + 8 = - 7.\]
\[E(g) = \lbrack - 7;14\rbrack.\]