Решебник по алгебре 9 класс Мерзляк Задание 129

 

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

Пояснение.

Решение.

\[1)\ 4 + 11x > 7 + 12x\]

\[11x - 12x > 7 - 4\]

\[- x > 3\]

\[x < - 3\]

\[Ответ:x \in ( - \infty; - 3).\]

\[2)\ 35x - 28 \leq 32x + 2\]

\[35x - 32x \leq 2 + 28\]

\[3x \leq 30\]

\[x \leq 10\]

\[Ответ:x \in ( - \infty;10\rbrack.\]

\[3)\ 3x - 10 < 6x + 2\]

\[3x - 6x < 2 + 10\]

\[- 3x < 12\]

\[x > - 4\]

\[Ответ:x \in ( - 4;\ + \infty).\]

\[4)\ 6x - 3 \geq 2x - 25\]

\[6x - 2x \geq - 25 + 3\]

\[4x \geq - 22\]

\[x \geq - 5,5\]

\[Ответ:x \in \lbrack - 5,5;\ + \infty).\]

\[\boxed{\mathbf{129.\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ 7 - 2x = 3x - 9\]

\[- 5x = - 16\]

\[x = \frac{16}{5} = 3\frac{1}{5}\]

\[x = 3,2.\]

\[2)\ 4(2 - 3x) = 10 - 7x\]

\[8 - 12x = 10 - 7x\]

\[- 5x = 2\]

\[x = - \frac{2}{5}\]

\[x = - 0,4.\]

\[3)\ 2 - 5(3x + 2,5) = 3x + 7,5\]

\[2 - 5x - 12,5 = 3x + 7,5\]

\[- 8x = 7,5 + 10,5\]

\[- 8x = 18\]

\[x = - \frac{18}{8} = - \frac{9}{4} = - 2\frac{1}{4}\]

\[x = - 2,25.\]

\[4)\ \frac{2x + 4}{3} = \frac{x - 1}{2}\]

\[2(2x + 4) = 3(x - 1)\]

\[4x + 8 = 3x - 3\]

\[x = - 11.\]

\[5)\ \frac{x + 9}{3} - \frac{x}{5} = 1\ \ \ \ | \cdot 15\]

\[5(x + 9) - 3x = 15\]

\[5x + 45 - 3x = 15\]

\[2x = - 30\]

\[x = - 15.\]

\[6)\ (3 - 0,6x)(7x + 1) = 0\]

\[- 0,6 \cdot 7 \cdot (x - 5)\left( x + \frac{1}{7} \right) = 0\]

\[x = 5;\ \ \ x = - \frac{1}{7}.\]