Question
Let $\mathrm{a}, \mathrm{b} \in R, \mathrm{b} \neq 0$, Define a function
$f(x)= \begin{cases}\operatorname{a} \sin \frac{\pi}{2}(x-1), & \text { for } x \leq 0 \\ \frac{\tan 2 x-\sin 2 x}{b x^{3}}, & \text { for } x>0\end{cases}$
If $f$ is continuous at $x=0$, then $10-a b$ is equal to ...... .