\[\boxed{\mathbf{17.}}\]
\[\textbf{а)}\ y = x^{5} - 5x - 4\sin( - x)\]
\[y( - x) =\]
\[= ( - x)^{5} - 5 \cdot ( - x) - 4\sin( - x) =\]
\[= - x^{5} + 5x + 4\sin(x) =\]
\[= - \left( x^{5} - 5x - 4\sin(x) \right) =\]
\[= - y(x).\]
\[Функция\ нечетная.\]
\[\textbf{б)}\ y = 4x^{7} - 5x^{3} - 5x\]
\[y( - x) =\]
\[= 4 \cdot ( - x)^{7} - 5 \cdot ( - x)^{3} - 5 \cdot ( - x) =\]
\[= - 4x^{7} + 5x^{3} + 5x =\]
\[= - \left( 4x^{7} - 5x^{3} - 5x \right) = - y(x).\]