Решебник по математике 6 класс Виленкин Часть 1, 2 Часть 2. Параграф 5. Решение уравнений Задание 89

\[\boxed{\text{5.\ 89}}\]

\[\textbf{а)}\ 4 \cdot (z - 6) - 3 \cdot (z - 3) = 8\]

\[4z - 24 - 3z + 9 = 8\]

\[z = 8 + 15\]

\[z = 23.\]

\[\textbf{б)} - 6 \cdot (6 - x) - 5x = 18\]

\[- 36 + 6x - 5x = 18\]

\[x = 18 + 36\]

\[x = 54.\]

\[\textbf{в)}\ \frac{1}{5} \cdot (5x - 10) - \frac{2}{9} \cdot (9x - 27) =\]

\[= 9\]

\[x - 2 - 2x + 6 = 9\]

\[- x + 4 = 9\]

\[- x = 9 - 4\]

\[- x = 5\]

\[x = - 5.\]

\[\textbf{г)}\ 4,2 \cdot (3z - 5) - 1,4 \cdot (5z - 3) =\]

\[= 5,6\]

\[12,6z - 21 - 7z + 4,2 = 5,6\]

\[5,6z - 16,8 = 5,6\]

\[5,6z = 5,6 + 16,8\]

\[5,6z = 22,4\]

\[z = 22,4\ :5,6 = 224\ :56\]

\[z = 4.\]