Решебник по математике 6 класс Виленкин ФГОС Часть 1, 2 Часть 2. П. 4. Действия с рациональными числами Задание 323

\[\boxed{\text{4.\ 323}}\]

\[\left| \text{ab} \right| = |a| \cdot |b|\]

\[a = 0,1;\ \ b = - 2:\]

\[\left| 0,1 \cdot ( - 2) \right| = |0,1| \cdot | - 2|\]

\[| - 0,2| = 0,1 \cdot 2\]

\[0,2 = 0,2.\]

\[a = - \frac{1}{2};\ \ b = 3:\]

\[\left| - \frac{1}{2} \cdot 3 \right| = \left| - \frac{1}{2} \right| \cdot |3|\]

\[\left| - \frac{3}{2} \right| = \frac{1}{2} \cdot 3\]

\[\frac{3}{2} = \frac{3}{2}.\]

\[При\ a > 0;b > 0:\]

\[\left| \text{ab} \right| = ab;\ \ |a| \cdot |b| = ab.\]

\[Например,\ a = 3;\ \ b = 4:\]

\[|3 \cdot 4| = |3| \cdot |4|\]

\[|12| = 3 \cdot 4\]

\[12 = 12.\]

\[При\ a > 0;b < 0:\]

\[\left| a \cdot ( - b) \right| = |a| \cdot | - b|\]

\[| - ab| = a \cdot b\]

\[ab = ab.\]

\[Например,\ a = 3;b = - 4:\]

\[\left| 3 \cdot ( - 4) \right| = |3 \cdot | - 4|\]

\[| - 12| = 3 \cdot 4\]

\[12 = 12.\]

\[При\ a < 0;b > 0:\]

\[| - a \cdot b| = | - a| \cdot |b|\]

\[| - ab| = a \cdot b\]

\[ab = ab.\]

\[Например,\ a = - 3;b = 4:\]

\[| - 3 \cdot 4| = | - 3| \cdot |4|\]

\[| - 12| = 3 \cdot 4\]

\[12 = 12.\]

\[При\ a < 0;b < 0:\]

\[\left| - a \cdot ( - b) \right| = | - a| \cdot | - b|\]

\[\left| \text{ab} \right| = a \cdot b\]

\[ab = ab.\]

\[Например,\ a = - 3;\ \ b = - 4:\]

\[\left| - 3 \cdot ( - 4) \right| = | - 3| \cdot | - 4|\]

\[|12| = 3 \cdot 4\]

\[12 = 12.\]