Решебник по алгебре 8 класс Мерзляк ФГОС Задание 766

 

\[\boxed{\mathbf{766\ (766).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ a² - 14ab + 40b^{2} =\]

\[= a^{2} - 10ab - 4ab + 40b^{2} =\]

\[= a(a - 10b) - 4b(a - 10b) =\]

\[= (a - 4b)(a - 10b)\]

\[2)\ 12b² + bc - 6c^{2} =\]

\[= 12b^{2} + 9bc - 8bc - 6c^{2} =\]

\[= 3b(4b + 3c) - 2c(4b + 3c) =\]

\[= (4b + 3c)(3b - 2c)\]

\[\boxed{\mathbf{7}\mathbf{6}\mathbf{6}\mathbf{\text{.\ }}Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ 2x² - 5x + 3 = 0\]

\[x_{1} + x_{2} = \frac{5}{2},\ \ x_{1} = 1\]

\[x_{1} \cdot x_{2} = \frac{3}{2},\ \ x_{2} = \frac{3}{2} = 1,5\]

\[Ответ:x = 1;x = 1,5.\]

\[2)\ 2x² + 5x + 3 = 0\]

\[x_{1} + x_{2} = - \frac{5}{2},\ \ x_{1} = - 1\]

\[x_{1} \cdot x_{2} = \frac{3}{2},\ \ x_{2} = - \frac{3}{2} = - 1,5\]

\[Ответ:\ x = - 1;\ x = - 1,5.\]

\[3)16x² - 23x + 7 = 0\]

\[x_{1} + x_{2} = \frac{23}{16},\ \ x_{1} = \frac{7}{16}\]

\[x_{1} \cdot x_{2} = \frac{7}{16},\ \ x_{2} = 1\]

\[Ответ:x = \frac{7}{16};x = 1.\]

\[4) - 8x^{2} - 19x + 27 = 0\]

\[x_{1} + x_{2} = - \frac{19}{8},\ \ \]

\[x_{1} = - \frac{27}{8} = - 3\frac{3}{8}\]

\[x_{1} \cdot x_{2} = - \frac{27}{8},\ \ x_{2} = 1\]

\[Ответ:\ x = - 3\frac{3}{8};x = 1.\]