[tex]\begin{gathered} When\text{ f\lparen x\rparen }<0,\text{ then the solution of f\lparen x\rparen is \lparen-}\infty,\text{ -1\rparen }\cup\text{ \lparen2,3\rparen} \\ When\text{ f\lparen x\rparen }\ge\text{ 0, then the solution of f\lparen x\rparen is }\lbrack\text{ -1, 2}\rbrack\cup\text{ }\lbrack3,\text{ }\infty) \end{gathered}[/tex]
