If the mean and variance of the frequency distribution are 9 and 15.08 respectively, then the value of α^2+β^2-α β is ____.

If the mean and variance of the frequency distribution

$\displaystyle x_i$	$\displaystyle 2$	$\displaystyle 4$	$\displaystyle 6$	$\displaystyle 8$	$\displaystyle 10$	$\displaystyle 12$	$\displaystyle 14$	$\displaystyle 16$
$\displaystyle f_i$	$\displaystyle 4$	$\displaystyle 4$	$\displaystyle \alpha$	$\displaystyle 15$	$\displaystyle 8$	$\displaystyle \beta$	$\displaystyle 4$	$\displaystyle 5$

are $\displaystyle 9$ and $\displaystyle 15.08$ respectively, then the value of $\displaystyle \alpha^2+\beta^2-\alpha \beta$ is $\displaystyle \_\_\_\_$.