/ 3 2 \ / 3 2 \
[CRootOf\x + 2*x - 9*x - 15, 0/, -3) U (3, CRootOf\x + 2*x - 9*x - 21, 0/]
$$x\ in\ \left[\operatorname{CRootOf} {\left(x^{3} + 2 x^{2} - 9 x - 15, 0\right)}, -3\right) \cup \left(3, \operatorname{CRootOf} {\left(x^{3} + 2 x^{2} - 9 x - 21, 0\right)}\right]$$
x in Union(Interval.Lopen(3, CRootOf(x^3 + 2*x^2 - 9*x - 21, 0)), Interval.Ropen(CRootOf(x^3 + 2*x^2 - 9*x - 15, 0), -3))
/ / / 3 2 \ \ / / 3 2 \ \\
Or\And\x <= CRootOf\x + 2*x - 9*x - 21, 0/, 3 < x/, And\CRootOf\x + 2*x - 9*x - 15, 0/ <= x, x < -3//
$$\left(x \leq \operatorname{CRootOf} {\left(x^{3} + 2 x^{2} - 9 x - 21, 0\right)} \wedge 3 < x\right) \vee \left(\operatorname{CRootOf} {\left(x^{3} + 2 x^{2} - 9 x - 15, 0\right)} \leq x \wedge x < -3\right)$$
((3 < x)∧(x <= CRootOf(x^3 + 2*x^2 - 9*x - 21, 0)))∨((x < -3)∧(CRootOf(x^3 + 2*x^2 - 9*x - 15, 0) <= x))