10. Given the set $A=\{x \mid 0<x \leqslant 3\}, B=\left\{x \mid x^{2}-2 a x+a \leqslant 0\right\}$. If $A \cup B=A$, then the range of real number $a$ is $\qquad$ .
10. $00 \\
f(3) \geqslant 0,
\end{array} \text { so we get } 0<a \leqslant \frac{9}{5} .\right.
$$