We will have the following:
We determine the x-intercepts as follows:
First, we factor the expression; that is:
[tex]x^3+2x^2-9x-18=(x^3+2x^2)+(-9x-18)[/tex][tex]=x^2(x+2)-9(x+2)=(x+2)(x^2-9)[/tex][tex]=(x+2)(x-3)(x+3)[/tex]
Now, we equal the expression to 0, that is:
[tex](x+2)(x-3)(x+3)=0\Rightarrow\begin{cases}x+2=0 \\ \\ x-3=0 \\ \\ x+3=0\end{cases}[/tex][tex]\Rightarrow\begin{cases}x=-2 \\ \\ x=3 \\ \\ x=-3\end{cases}[/tex]
So, the x-intercepts are located at:
[tex](-2,0)[/tex][tex](-3,0)[/tex][tex](3,0)[/tex]
We can see it as follows: