\[\boxed{\text{1106.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[\textbf{а)} - 0,8x + 12 = 0\]
\[0,8x = 12\]
\[x = 15\]
\[Ответ:x = 15.\]
\[\textbf{б)}\ (3x - 10)(x + 6) = 0\]
\(3x - 10 = 0\ \ \)
\[3x = 10\]
\[x = 3\frac{1}{3}.\]
\[x + 6 = 0\]
\[x = - 6.\]
\[Ответ:x = 3\frac{1}{3};\ \ x = - 6.\]
\[\textbf{в)}\ \ \frac{4 + 2x}{x^{2} + 5} = 0\]
\[4 + 2x = 0\]
\[x = - 2\]
\[Ответ:x = - 2.\]
\[\textbf{г)}\ \frac{6}{(x - 1)(x + 8)} = 0 \Longrightarrow нулей\ \]
\[не\ существует.\]
\[Ответ:нулей\ функции\ \]
\[не\ существует.\]