For \( \alpha, \beta, \gamma \in \mathbb{R} \), if \( \lim_{x \to 0} \dfrac{x^{2}\sin(\alpha x) + (\gamma-1)e^{\ x^{2}}}{\sin 2x - \beta x} = 3 \), then \( \beta + \gamma - \alpha \) is equal to:
\( 7 \)
\( 6 \)
\( -1 \)
\( 4 \)