9. Let $\alpha, \beta$ satisfy the equations $\alpha^{3}-3 \alpha^{2}+5 \alpha-4=0, \beta^{3}-3 \beta^{2}+5 \beta-2=0$, then $\alpha+\beta=$
$$
(\alpha-1)^{3}+2(\alpha-1)=1,(\beta-1)^{3}+2(\beta-1)=-1 \Rightarrow \alpha-1=1-\beta \Rightarrow \alpha+\beta=2 .
$$