Решебник по алгебре 7 класс Мерзляк ФГОС Задание 485

 

\[\boxed{\text{485\ (485).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

Пояснение.

Решение.

\[\boxed{\text{485.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)\ \frac{6x - 7}{5} - \frac{3x + 1}{6} = \frac{11 - x}{15}\ \ | \cdot 30\]

\[6(6x - 7) - 5(x + 1) = 2(11 - x)\]

\[36x - 42 - 5x - 5 = 22 - 2x\]

\[31x + 2x = 22 + 47\]

\[33x = 69\]

\[x = 3.\]

\[2)\ \frac{5x - 3}{9} - \frac{4x + 3}{6} = x - 1\ \ | \cdot 18\]

\[2(5x - 3) - 3(4x + 3) = 18(x - 1)\]

\[10x - 6 - 12x - 9 = 18x - 18\]

\[- 2x - 18x = - 18 + 15\]

\[- 20x = - 3\]

\[x = \frac{3}{20} = 0,15.\]

\[3)\ \frac{8x - 5}{3} - \frac{4x + 3}{4} + \frac{2 - 9x}{2} = - 3\ \ | \cdot 12\]

\[4(8x - 5) - 3(4x + 3) + 6(2 - 9x) = - 36\]

\[32x - 20 - 12x - 9 + 12 - 54x = - 36\]

\[- 34x = - 36 + 17\]

\[- 34x = - 19\]

\[x = \frac{19}{34}.\]

\[4)\ \frac{8x^{2} - 3x}{16} - \frac{6x^{2} + 1}{12} = - 1\ \ | \cdot 48\]

\[3\left( 8x^{2} - 3x \right) - 4\left( 6x^{2} + 1 \right) = - 48\]

\[24x^{2} - 9x - 24x^{2} - 4 = - 48\]

\[- 9x = - 48 + 4\]

\[- 9x = - 44\]

\[x = \frac{44}{9} = 5\frac{4}{9}.\]