Решебник по алгебре 7 класс Макарычев ФГОС Задание 129

 

\[\boxed{\text{129.}\text{\ }еуроки - ответы\ на\ пятёрку}\]

\[Единичный\ отрезок\ равен\ \]

\[двум\ клеткам.\]

\[\boxed{\text{129\ (129).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[\textbf{а)}\ 2x + 9 = 13 - x\]

\[2x + x = 13 - 9\]

\[3x = 4\]

\[x = 4\ :3\]

\[x = \frac{4}{3}\]

\[x = 1\frac{1}{3}\]

\[Ответ:x = 1\frac{1}{3}.\]

\[\textbf{б)}\ 14 - y = 19 - 11y\]

\[- y + 11y = 19 - 14\]

\[10y = 5\]

\[y = 5\ :10\]

\[y = 0,5\]

\[Ответ:y = 0,5.\]

\[\textbf{в)}\ 0,5a + 11 = 4 - 3a\]

\[0,5a + 3a = 4 - 11\]

\[3,5a = - 7\]

\[a = - 7\ :3,5\]

\[a = - 70\ :35\]

\[a = - 2\]

\[Ответ:a = - 2.\]

\[\textbf{г)}\ 1,2n + 1 = 1 - n\]

\[1,2n + n = 1 - 1\]

\[2,2n = 0\]

\[n = 0\]

\[Ответ:n = 0.\]

\[\textbf{д)}\ 1,7 - 0,3m = 2 + 1,7m\]

\[- 0,3m - 1,7m = 2 - 1,7\]

\[- 2m = 0,3\]

\[m = 0,3\ :( - 2)\]

\[m = - 3\ :20\]

\[m = - 0,15\]

\[Ответ:m = - 0,15.\]

\[\textbf{е)}\ 0,8x + 14 = 2 - 1,6x\]

\[0,8x + 1,6x = 2 - 14\]

\[2,4x = - 12\]

\[x = - 12\ :2,4\]

\[x = - 120\ :24\]

\[x = - 5\]

\[Ответ:x = - 5.\]

\[\textbf{ж)}\ 15 - p = \frac{1}{3}p - 1\]

\[- p - \frac{1}{3}p = - 1 - 15\]

\[- 1\frac{1}{3}p = - 16\]

\[\frac{4}{3}p = 16\]

\[p = 16\ :\frac{4}{3}\]

\[p = 16 \cdot \frac{3}{4} = 4 \cdot 3\]

\[p = 12\]

\[Ответ:p = 12.\]

\[\textbf{з)}\ 1\frac{1}{3}x + 4 = \frac{1}{3}x + 1\]

\[1\frac{1}{3}x - \frac{1}{3}x = 1 - 4\]

\[x = - 3\ \]

\[Ответ:x = - 3.\]

\[\textbf{и)}\ z - \frac{1}{2}z = 0\]

\[\frac{1}{2}z = 0\]

\[z = 0\]

\[Ответ:z = 0.\]

\[к)\ x - 4x = 0\]

\[- 3x = 0\]

\[x = 0\]

\[Ответ:x = 0.\]

\[л)\ x = - x\]

\[x + x = 0\]

\[2x = 0\ \]

\[x = 0\]

\[Ответ:x = 0.\]

\[м)\ 5y = 6y\]

\[5y - 6y = 0\]

\[- y = 0\]

\[y = 0\]

\[Ответ:y = 0.\]