ГДЗ по алгебре 8 класс Макарычев ФГОС Задание 884

\[\boxed{\text{884.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]

\[3 < a < 4;\ \ \ 4 < b < 5\]

\[\textbf{а)}\ a + b = ?\]

\[3 + 4 < a + b < 4 + 5\]

\[7 < a + b < 9\]

\[\textbf{б)}\ a - b = a + ( - b)\]

\[- 5 < - b < - 4\]

\[3 - 5 < a + ( - b) < 4 - 4\]

\[- 2 < a - b < 0\]

\[\textbf{в)}\ ab = ?\]

\[3 \cdot 4 < a \cdot b < 4 \cdot 5\]

\[12 < ab < 20\]

\[\textbf{г)}\frac{a}{b} = a \cdot \frac{1}{b}\]

\[\frac{1}{4} > \frac{1}{b} > \frac{1}{5}\]

\[4 \cdot \frac{1}{4} > a \cdot \frac{1}{b} > 3 \cdot \frac{1}{5}\]

\[1 > a \cdot \frac{1}{b} > \frac{3}{5}\]

\[\frac{3}{5} < \frac{a}{b} < 1\]