ГДЗ по алгебре 7 класс Макарычев Задание 745

\[\boxed{\text{745\ (745).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[\textbf{а)}\ (4 - 2x) + (5x - 3) =\]

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

\[4 - 2x + 5x - 3 = x - 2 - x - 3\]

\[3x = - 5 - 1\]

\[3x = - 6\]

\[x = - 2\]

\[Ответ:x = - 2.\]

\[\textbf{б)}\ 5 - 3y - (4 - 2y) =\]

\[= y - 8 - (y - 1)\]

\[5 - 3y - 4 + 2y = y - 8 - y + 1\]

\[- y = - 7 - 1\]

\[- y = - 8\]

\[y = 8\]

\[Ответ:y = 8.\]

\[\textbf{в)}\ 7 - 1\frac{1}{2}a + \left( \frac{1}{2}a - 5\frac{1}{2} \right) =\]

\[= 2a + \frac{3}{4} - \left( \frac{1}{2} + \frac{1}{2}a \right)\]

\[7 - \frac{3}{2}a + \frac{1}{2}a - \frac{11}{2} - 2a + \frac{1}{2} + \frac{1}{2}a =\]

\[= \frac{3}{4}\]

\[- \frac{5}{2}a = \frac{3}{4} - 7 + \frac{10}{2}\]

\[- \frac{5}{2}a = - \frac{5}{4}\]

\[a = \frac{5}{4}\ :\frac{5}{2} = \frac{5}{4} \cdot \frac{2}{5} = \frac{1}{2} = 0,5\]

\[a = 0,5\]

\[Ответ:a = 0,5.\]

\[\textbf{г)} - 3,6 - (1,5x + 1) =\]

\[= - 4x - 0,8 - (0,4x - 2)\]

\[- 3,6 - 1,5x - 1 =\]

\[= - 4x - 0,8 - 0,4x + 2\]

\[- 1,5x + 4,4x = 4,6 + 1,2\]

\[2,9x = 5,8\]

\[x = 5,8\ :2,9 = 58\ :29\]

\[x = 2\]

\[Ответ:x = 2.\]