Решебник по алгебре 7 класс Мерзляк ФГОС Задание 200

 

\[\boxed{\text{200\ (200).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)\ 9 \cdot (2x - 1) - 5 \cdot (11 - x) =\]

\[= 3 \cdot (x + 4)\]

\[18x - 9 - 55 + 5x = 3x + 12\]

\[23x - 3x = 12 + 9 + 55\]

\[20x = 76\]

\[x = \frac{76}{20}\]

\[x = 3,8.\]

\[Ответ:3,8.\]

\[2)\ 5x - 26 = 12x - 7 \cdot (x - 4)\]

\[5x - 26 = 12x - 7x + 28\]

\[5x + 7x - 12x = 28 + 26\]

\[0x = 54\]

\[Ответ:корней\ нет.\ \]

\[\boxed{\text{200.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)\ 14 - 6x;\ \]

\[x = - 2:\]

\[14 - 6 \cdot ( - 2) = 14 + 12 = 26.\]

\[x = 0:\]

\[14 - 6 \cdot 0 = 14 - 0 = 14.\]

\[x = \frac{3}{8}:\]

\[14 - 6 \cdot \frac{3}{8} = 14 - \frac{6 \cdot 3}{8} =\]

\[= 14 - \frac{3 \cdot 3}{4} = 14 - \frac{9}{4} =\]

\[= 14 - 2\frac{1}{4} = 11\frac{3}{4}.\]

\[2)\ a^{2} + 3;\]

\[a = 7:\]

\[7^{2} + 3 = 49 + 3 = 52.\]

\[a = 0,4:\]

\[(0,4)^{2} + 3 = 0,16 + 3 = 3,16.\]

\[a = - 1\frac{1}{3}:\]

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

\[= \frac{16}{9} + 3 = 1\frac{7}{9} + 3 = 4\frac{7}{9}.\]

\[3)\ (2m - n)n;\]

\[m = 0,2;n = - 0,6:\]

\[(2 \cdot 0,2 - 1) \cdot ( - 0,6) =\]

\[= (0,4 - 1) \cdot ( - 0,6) =\]

\[= - 0,6 \cdot ( - 0,6) = 0,36.\ \ \]