\[\boxed{\text{189.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[\textbf{а)}\ f(x) = x^{3} - 7x\]
\[f( - x) = - x^{3} + 7x =\]
\[= - \left( x^{3} - 7x \right) = - f(x).\]
\[Функция\ нечетная.\]
\[\textbf{б)}\ f(x) = \frac{x^{2} + 9}{x};\ \ x \neq 0\]
\[f( - x) = \frac{x^{2} + 9}{- x} = - \frac{- x^{2} - 9}{x}.\]
\[Функция\ ни\ четная,\ \]
\[ни\ нечетная.\]