$${\alpha = \frac{\omega^2 - \omega_0^2}{2(\theta - \theta_0)} = \frac{(2,00\, \mathrm{rad/s})^2 - (3,40\, \mathrm{rad/s})^2}{2(125,7\, \mathrm{rad})} \\ = \underline{\underline{-0,0301\, \mathrm{rad/s^2}}}}$$