\[\boxed{\text{1133.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[y = \frac{4}{x}.\]
\[\textbf{а)}\ \frac{4}{x} = 8\]
\[x = \frac{1}{2}.\]
\[\frac{4}{x} = - 8\]
\[x = - \frac{1}{2}.\]
\[\textbf{б)}\ \frac{4}{x} < 4;\ \ \ x \neq 0\]
\[x > 1.\]
\[При\ x \in (1; + \infty).\]
\[\textbf{в)}\ \frac{4}{x} > 2;\ \ \ x \neq 0\]
\[x < 2.\]
\[При\ x \in (0;2).\]