\[Стр.\ 63.\]
\[36.\ Свойства\ действий\ \]
\[с\ рациональными\ числами\]
\[\boxed{\mathbf{1.}}\]
\[a + b = b + a;\]
\[a + (b + c) = (a + b) + c.\]
\[\boxed{\mathbf{2.}}\]
\[a \cdot b = b \cdot a;\]
\[a \cdot (b \cdot c) = (a \cdot b) \cdot c.\]
\[\boxed{\mathbf{3.}}\]
\[a \cdot (b + c) = a \cdot b + a \cdot c.\]
\[\boxed{\mathbf{4.}}\]
\[Выражение\] | \[Сумма\] | ||
---|---|---|---|
\[Положительных\ \] \[чисел\] |
\[Отрицательных\ \] \[чисел\] |
\[Общая\] | |
\[- 20 + 97 + 56 -\] \[- 34 - 16 + 45\] |
\[198\] | \[- 70\] | \[128\] |
\[- 34 + 26 - 100 +\] \[+ 14 - 6\] |
\[40\] | \[- 140\] | \[- 100\] |
\[8,26 - 4,3 +\] \[+ 9,74 - 5,7\] |
\[18\] | \[- 10\] | \[8\] |
\[6\frac{2}{7} - 3\frac{1}{8} + 9\frac{5}{7} + 3\] | \[19\] | \[- 3\frac{1}{8}\] | \[15\frac{7}{8}\] |
\[10,7 - \frac{2}{11} + 0,3 - 10\] | \[11\] | \[- 10\frac{2}{11}\] | \[\frac{9}{11}\] |
\[Переместительный\ и\ \]
\[сочетательный.\]