\[\begin{array}{*{20}{l}}
\begin{array}{l}
1.{\rm{ }}4{x^2}{\rm{ }} - {\rm{ }}25{\rm{ }} - {\rm{ }}\left( {2x{\rm{ }} - {\rm{ }}5} \right)\left( {x{\rm{ }} + {\rm{ }}7} \right){\rm{ }} = {\rm{ }}0\\
\Leftrightarrow \left( {2x - 5} \right)\left( {2x + 5} \right) - \left( {2x - 5} \right)\left( {x + 7} \right) = 0\\
\Leftrightarrow \left( {2x - 5} \right)\left( {2x + 5 - x - 7} \right) = 0\\
\Leftrightarrow \left( {2x - 5} \right)\left( {x - 2} \right) = 0\\
\Leftrightarrow \left[ \begin{array}{l}
2x - 5 = 0\\
x - 2 = 0
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
x = \frac{5}{2}\\
x = 2
\end{array} \right.\\
vay:S = \{ \frac{5}{2};2\}
\end{array}\\
\begin{array}{l}
2.{\rm{ }}{x^3}{\rm{ }} + {\rm{ }}27{\rm{ }} + {\rm{ }}\left( {x{\rm{ }} + {\rm{ }}3} \right)\left( {x{\rm{ }} - {\rm{ }}9} \right){\rm{ }} = {\rm{ }}0\\
\Leftrightarrow \left( {x + 3} \right)\left( {{x^2} - 3x + 9} \right) + \left( {x + 3} \right)\left( {x - 9} \right) = 0\\
\Leftrightarrow \left( {x + 3} \right)\left( {{x^2} - 3x + 9 + x - 9} \right) = 0\\
\Leftrightarrow \left( {x + 3} \right)\left( {{x^2} - 2x} \right) = 0\\
\Leftrightarrow x\left( {x + 3} \right)\left( {x - 2} \right) = 0\\
\Leftrightarrow \left[ \begin{array}{l}
x = 0\\
x + 3 = 0\\
x - 2 = 0
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
x = 0\\
x = - 3\\
x = 2
\end{array} \right.\\
vay:S = \{ 0; - 3;2\}
\end{array}\\
\begin{array}{l}
3.{\rm{ }}2{x^3}{\rm{ }} + {\rm{ }}3{x^2}{\rm{ }} + {\rm{ }}2x{\rm{ }} + {\rm{ }}3{\rm{ }} = {\rm{ }}0\\
\Leftrightarrow {x^2}\left( {2x + 3} \right) + \left( {2x + 3} \right) = 0\\
\Leftrightarrow \left( {2x + 3} \right)\left( {{x^2} + 1} \right) = 0\\
\Leftrightarrow 2x + 3 = 0\left( {do:{x^2} + 1 > 0} \right)\\
\Leftrightarrow x = \frac{{ - 3}}{2}\\
vay:x = \frac{{ - 3}}{2}
\end{array}
\end{array}\]