\[2x^{2} + ax - 3 = 0\ \ \]
\[x_{1}^{2} + x_{2}^{2} = \frac{37}{4}\]
\[\left\{ \begin{matrix} x_{1} + x_{2} = - \frac{a}{2} \\ x_{1} \cdot x_{2} = - \frac{3}{2}\text{\ \ } \\ \end{matrix} \right.\ \]
\[x_{1}^{2} + x_{2}^{2} = \left( x_{1} + x_{2} \right)^{2} - 2x_{1}x_{2}\]
\[\left( - \frac{a}{2} \right)^{2} - 2 \cdot \left( - \frac{3}{2} \right) = \frac{37}{4}\]
\[\frac{a^{2}}{4} + 3 = \frac{37}{4}\ \ \ \ \ \ \ \ \ \ | \cdot 4\]
\[a^{2} + 12 = 37\]
\[a^{2} = 25\]
\[a = \pm 5.\]
\[Ответ:a = \pm 5.\]