If the domain of the function \( f(x) = \sin^{-1}\!\left(\dfrac{x - 1}{2x + 3}\right) \) is \( \mathbb{R} - (\alpha, \beta) \), then \( 12\alpha\beta \) is equal to:
\( 40 \)
\( 32 \)
\( 24 \)
\( 36 \)