ГДЗ по алгебре 8 класс Макарычев ФГОС Задание 943

\[\boxed{\text{943.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]

\[\textbf{а)}\ 5 \cdot (x - 1) + 7 \leq 1 -\]

\[- 3 \cdot (x + 2)\]

\[5x - 5 + 7 \leq 1 - 3x - 6\]

\[5x + 3x \leq 1 - 6 + 5 - 7\]

\[8x \leq - 7\]

\[x \leq - \frac{7}{8} \Longrightarrow \ \ x \in \left( - \infty;\ - \frac{7}{8} \right\rbrack\]

\[\textbf{б)}\ 4 \cdot (a + 8) -\]

\[- 7 \cdot (a - 1) < 12\]

\[4a + 32 - 7a + 7 < 12\]

\[- 3a < 12 - 32 - 7\]

\[- 3a < - 27\]

\[a > 9 \Longrightarrow \ \ a \in (9;\ + \infty)\]

\[\textbf{в)}\ 4 \cdot (b - 1,5) - 1,2 \geq 6b - 1\]

\[4b - 6 - 1,2 \geq 6b - 1\]

\[4b - 6b \geq - 1 + 6 + 1,2\]

\[- 2b \geq 6,2\]

\[b \leq - 3,1 \Longrightarrow \ \ b \in \left( \mathbf{- \infty}\mathbf{;\ -}3,1 \right\rbrack\ \]

\[\textbf{г)}\ 1,7 - 3 \cdot (1 - m) \leq\]

\[\leq - (m - 1,9)\]

\[1,7 - 3 + 3m \leq - m + 1,9\]

\[3m + m \leq 1,9 - 1,7 + 3\]

\[4m \leq 3,2\]

\[m \leq \frac{3,2}{4}\text{\ \ }\]

\[m \leq \frac{32}{40}\]

\[m \leq 0,8, \Longrightarrow \ m \in ( - \infty;0,8\rbrack\]

\[\textbf{д)}\ 4x > 12 \cdot (3x - 1) -\]

\[- 16 \cdot (x + 1)\]

\[4x > 36x - 12 - 16x - 16\]

\[4x - 20x > - 28\]

\[- 16x > - 28\ \]

\[x < \frac{28}{16}\]

\[x < 1,75 \Longrightarrow \ \ x \in ( - \infty;1,75)\]

\[\textbf{е)}\ a + 2 < 5 \cdot (2a + 8) +\]

\[+ 13 \cdot (4 - a)\]

\[a + 2 < 10a + 40 + 52 - 13a\]

\[a - 10a + 13a < 40 + 52 - 2\]

\[4a < 90\]

\[a < 22,5 \Longrightarrow \ \ a \in ( - \infty;22,5)\]

\[\textbf{ж)}\ 6y - (y + 8) -\]

\[- 3 \cdot (2 - y) \leq 2\]

\[6y - y - 8 - 6 + 3y \leq 2\]

\[8y \leq 2 + 8 + 6\]

\[8y \leq 16\]

\[y \leq 2 \Longrightarrow \ \ y \in ( - \infty;2\rbrack\]