\[3x² + 5x + 2a\]
\[3x^{2} + 5x + 2a = 0\]
\[D \geq 0:\ \ \]
\[D = 25 - 4 \cdot 3 \cdot 2a = 25 - 24a\]
\[25 - 24a \geq 0\]
\[24a \leq 25\]
\[a \leq \frac{25}{24}\]
\[a \leq 1\frac{1}{24}\]
\[Ответ:\left( - \infty;1\frac{1}{24} \right\rbrack.\]