If $\int \frac{2 x^{2}+5 x+9}{\sqrt{x^{2}+x+1}} \mathrm{~d} x=x \sqrt{x^{2}+x+1}+\alpha \sqrt{x^{2}+x+1}+\beta \log _{\mathrm{e}}\left|x+\frac{1}{2}+\sqrt{x^{2}+x+1}\right|+\mathrm{C}$, where $C$ is the constant of integration, then $\alpha+2 \beta$ is equal to $\_\_\_\_$ .