/ 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 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//
((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))