ГДЗ по алгебре 7 класс Макарычев Задание 698

\[\boxed{\text{698\ (698).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[\textbf{а)}\ 5 + x^{2} = (x + 1)(x + 6)\]

\[5 + x^{2} = x^{2} + 6x + x + 6\]

\[5 + x^{2} - x^{2} - 7x - 6 = 0\]

\[- 7x = 1\]

\[x = - \frac{1}{7}\]

\[Ответ:x = - \frac{1}{7}.\]

\[\textbf{б)}\ 2x(x - 8) = (x + 1)(2x - 3)\]

\[2x^{2} - 16x = 2x^{2} - 3x + 2x - 3\]

\[2x^{2} - 16x - 2x^{2} + x + 3 = 0\]

\[- 15x = - 3\]

\[x = \frac{3}{15} = \frac{1}{5}\]

\[x = 0,2\]

\[Ответ:x = 0,2.\]

\[- 2x = - 7\]

\[x = 3,5\]

\[Ответ:x = 3,5.\]

\[\textbf{г)}\ x^{2} + x(6 - 2x) =\]

\[= (x - 1)(2 - x) - 2\]

\[3x = - 4\]

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

\[Ответ:x = - 1\frac{1}{3}.\]