Решебник по алгебре 9 класс Мерзляк Задание 123

 

\[\boxed{\text{123\ (123).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

Пояснение.

Решение.

\[7 - 2b > 0\]

\[7 > 2b\]

\[b < 3,5\]

\[Ответ:при\ b \in ( - \infty;3,5).\]

\[\boxed{\mathbf{123.\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ x + 4 = 15\]

\[x = 11.\]

\[3x = 33\]

\[x = 11.\]

\[Равносильны.\]

\[2)\ 7x + 85 = 3x + 16\]

\[4x = - 69\]

\[x = - \frac{69}{4}.\]

\[7x - 16 = 3x - 85\]

\[4x = 69\]

\[x = \frac{69}{4}.\]

\[Неравносильны.\]

\[3)\ x - 9 = 0\]

\[x = 9.\]

\[x(x - 9) = 0\]

\[x = 0;x = 9.\]

\[Неравносильны.\]

\[4)\ \frac{16}{x} = 0\]

\[нет\ корней.\]

\[x^{2} = - 16\]

\[нет\ корней.\]

\[Равносильны.\]

\[5)\ \frac{8x - 9}{5} = \frac{4x - 11}{6}\ \ | \cdot 30\]

\[6(8x - 9) = 5(4x - 11).\]

\[6(8x - 9) = 5(4x - 11).\]

\[Равносильны.\]

\[6)\ \frac{x^{2} - 4}{x - 2} = 0;\ \ \ \ x \neq 2\]

\[x^{2} - 4 = 0\]

\[x^{2} = 4\]

\[x = \pm 2\]

\[x = - 2.\]

\[x^{2} - 4 = 0\]

\[x^{2} = 4\]

\[x = \pm 2.\]

\[Неравносильны.\]