\[\boxed{\text{72\ (72).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[f(x) = \frac{0,5x - 1}{6}\]
\[\textbf{а)}\ f(x) = 0:\]
\[\frac{0,5x - 1}{6} = 0\ \ \ \]
\[0,5x - 1 = 0\]
\[0,5x = 1\]
\[x = 2.\]
\[Ответ:при\ x = 2.\]
\[\textbf{б)}\ f(x) > 0:\]
\[\frac{0,5x - 1}{6} > 0\]
\[0,5x - 1 > 0\]
\[0,5x > 1\]
\[x > 2.\]
\[Ответ:при\ x > 2.\]
\[\textbf{в)}\ f(x) < 0:\ \]
\[\frac{0,5x - 1}{6} < 0\]
\[0,5x - 1 < 0\]
\[0,5x < 1\]
\[x < 2.\]
\[Ответ:при\ x < 2.\]