9.(2023春•怀仁市期末)函数f(x)=x3−3xf(x)=x^{3}-3xf(x)=x3−3x在区间(−2,a)(-2,a)(−2,a)上有最大值,则aaa的取值范围是 ___(−1(-1(−1[,]2]2]2]___.