\[\boxed{\text{211\ (211).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1)\ 2x + 4 = 0\ \ и\ \ x + 2 = 0\]
\[x = - 2\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 2\]
\[2)\ x^{2} - 9 = 0\ \ \ и\ \ \ 3x^{2} = 27\]
\[\left\{ \begin{matrix} x = 3\ \ \ \\ x = - 3 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ }\left\{ \begin{matrix} x = 3\ \ \ \\ x = - 3 \\ \end{matrix} \right.\ \]
\[3)\ 4x - 2 \cdot (2x + 1) = - 2\]
\[и\ \ 3 \cdot (3x + 1) - 9x = 3x\]
\[4)\ x^{2} + 4 = 0\ \ и\ \ \ x^{2} + 16 = 0\]