Решебник по алгебре 7 класс Мерзляк ФГОС Задание 1167

 

\[\boxed{\text{1167\ (1167).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[(3x - 1)(x + a) =\]

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

\[3x^{2} + 3\text{ax} - x - a =\]

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

\[3\text{ax} - 2x = a - 2\]

\[x \cdot (3a - 2) = a - 2\]

\[3a - 2 = 0\]

\[3a = 2\]

\[a = \frac{2}{3}\]

\[Ответ:a = \frac{2}{3}\text{.\ }\]

\[\boxed{\text{1167.\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)\ x - y = 4\ \ \]

\[y = x - 4\]

\[2)\ 4x + y = 3\ \ \]

\[y = 3 - 4x\]

\[3)\ x - 5y = 5\]

\[x = 5 + 5y\]

\[4)\ 3x + 2y = 6\ \]

\[2y = 6 - 3x\]

\[y = \frac{6 - 3x}{2} = 3 - 1,5x\]

\[5)\ 5x - 3y = 21\]

\[3y = 5x - 21\]

\[y = \frac{5}{3}x - 7\]

\[6)\ 0,2x + \frac{2}{3}y = 1\]

\[\frac{2}{3}y = 1 - 0,2x\]

\[y = \frac{3}{2} - 0,3x\]

\[y = 1,5 - 0,3x\]