Answer:
[tex]→ {x}^{3} + 2 {x}^{2} - 9x - 18 \\ = {x}^{2} (x + 2) - 9(x + 2) \\ = (x + 2)( {x}^{2} - 9) \\ = \boxed{(x + 2)(x + 3)(x - 3)}[/tex]