Let α, β be the roots of the equation x^2-x+2=0 with Im (α)> Im (β). Then α^6+α^4+β^4-5 α^2 is equal to ____.

Let $\displaystyle \alpha, \beta$ be the roots of the equation $\displaystyle x^2-x+2=0$ with $\displaystyle \operatorname{Im}(\alpha)>\operatorname{Im}(\beta)$. Then $\displaystyle \alpha^6+\alpha^4+\beta^4-5 \alpha^2$ is equal to $\displaystyle \_\_\_\_$.