\[\begin{array}{l}
{\text{Решите уравнение:}} \hfill \\
3 - {x^2} + 2 \cdot x = \sqrt {1 - {x^2}} \cdot \left( {2{x^2} + 4x + 3} \right) \hfill \\
\end{array}\]
\[\begin{array}{l}
3 - {x^2} + 2 \cdot x = \sqrt {1 - {x^2}} \cdot \left( {2{x^2} + 4x + 3} \right) \Leftrightarrow \hfill \\
4{x^6} + 16{x^5} + 25{x^4} + 4{x^3} - 21{x^2} - 12x = 0 \Leftrightarrow \hfill \\
x\left( {x + 1} \right)\left( {4{x^2} - 3} \right)\left( {{x^2} + 3x + 4} \right) = 0 \hfill \\
\end{array}\]
\[0; - 1; \pm \frac{{\sqrt 3 }}{2}\]