Решебник по алгебре 9 класс Мерзляк Задание 30

\[\boxed{\text{30\ (30).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[a > 0;\ \ b > 0;\ \ c < 0;\ \ d < 0.\]

\[1)\ bc = - bc < 0\]

\[2)\ cd = ( - c)( - d) > 0\]

\[3)\ \frac{a}{b} > 0\]

\[4)\ \frac{\text{ab}}{c} = \frac{\text{ab}}{- c} < 0\]

\[5)\ \frac{\text{ac}}{d} = \frac{- ac}{- d} > 0\]

\[6)\ \frac{a}{\text{bc}} = \frac{a}{- bc} < 0\]

\[7)\ abcd = ab( - c)( - d) =\]

\[= abcd > 0\]

\[8)\ \frac{b}{\text{acd}} = \frac{b}{a( - c)( - d)} > 0\]