\[Стр.\ 55.\]
\[\boxed{\mathbf{12.}}\]
\[x\] | \[- 2\] | \[- 1\] | \[0\] | \[1\] | \[2\] | \[- \frac{1}{2}\] | \[\frac{1}{2}\] |
---|---|---|---|---|---|---|---|
\[y\] | \[5\] | \[0\] | \[- 3\] | \[- 4\] | \[- 3\] | \[- 1\frac{3}{4}\] | \[- 3\frac{3}{4}\] |
\[\boxed{\mathbf{13.}}\]
\[a\] | \[- 5\] | \[7\] | \[- 8\] | \[2\] | \[- 6\] | \[12\] | \[0,7\] | \[- 0,9\] | \[- 0,8\] | \[- \frac{1}{4}\] | \[- \frac{1}{3}\] |
---|---|---|---|---|---|---|---|---|---|---|---|
\[b\] | \[6\] | \[- 4\] | \[3\] | \[- 9\] | \[- 8\] | \[30\] | \[- 0,3\] | \[0,6\] | \[- 0,4\] | \[\frac{1}{2}\] | \[- \frac{1}{6}\] |
a+b | \[1\] | \[3\] | \[- 5\] | \[- 7\] | \[- 14\] | \[42\] | \[0,4\] | \[- 0,3\] | \[- 1,2\] | \[\frac{1}{4}\] | \[- \frac{1}{2}\] |
a-b | \[- 11\] | \[11\] | \[- 11\] | \[11\] | \[2\] | \[- 18\] | \[1\] | \[- 1,5\] | \[- 0,4\] | \[- \frac{3}{4}\] | \[- \frac{1}{6}\] |
\[\text{ab}\] | \[- 30\] | \[- 28\] | \[- 24\] | \[- 18\] | \[48\] | \[360\] | \[- 0,21\] | \[- 0,54\] | \[0,32\] | \[- \frac{1}{8}\] | \[\frac{1}{18}\] |
\[\boxed{\mathbf{14.}}\]
\[\textbf{а)}\ 1,5\ км = 1500\ м;\ \ \]
\[1500 \cdot 0,6 = 900\ (м) - ширина.\]
\[1500 \cdot 900 = 1\ 350\ 000\ \left( м^{2} \right) -\]
\[площадь\ участка.\]
\[0,2 \cdot 1\ 350\ 000 =\]
\[= 270\ 000\ \left( м^{2} \right) = 27\ (га) -\]
\[площадь\ леса.\]
\[Ответ:27\ га.\]
\[\textbf{б)}\ (230,4 - 153,6)\ :2 =\]
\[= 76,8\ :2 = 38,4\ (т) - царь -\]
\[пушка.\ \]
\[Ответ:38,4\ т.\]
\[\textbf{в)}\ Пусть\ \text{x\ }кг - весит\ рыба.\]
\[x = \frac{3}{4} + \frac{3}{4}x\]
\[x - \frac{3}{4}x = \frac{3}{4}\]
\[\frac{1}{4}x = \frac{3}{4}\]
\[x = \frac{3}{4}\ :\frac{1}{4} = \frac{3 \cdot 4}{4} = 3\ (кг) -\]
\[весит\ рыба.\]
\[Ответ:3\ кг.\]