Let \( a > 0 \) be a root of the equation \( 2x^{2} + x - 2 = 0 \). If \(\displaystyle \lim_{x \to \frac{1}{a}} \frac{16\left(1 - \cos\big(2 + x - 2x^{2}\big)\right)}{(1 - a x)^{2}} = \alpha + \beta \sqrt{17} \), where \( \alpha, \beta \in \mathbb{Z} \), then \( \alpha + \beta \) is equal to \( \_\_\_\_\_\_ \).