[tex]\begin{gathered} 6x^3-18x^2=240x \\ 6x^3-18x^2-240x=240x-240x \\ 6x^3-18x^2-240x=0 \\ 6x\mleft(x+5\mright)\mleft(x-8\mright)=0 \\ x=0\quad \mathrm{or}\quad \: x+5=0\quad \mathrm{or}\quad \: x-8=0 \end{gathered}[/tex]
then
[tex]\begin{gathered} x+5=0 \\ x+5-5=0-5 \\ x=-5 \end{gathered}[/tex]
or
[tex]\begin{gathered} x-8=0 \\ x-8+8=0+8 \\ x=8 \end{gathered}[/tex]
solutions
x = 0
x = - 5
x = 8
