We can multiply polynomials by using a GRID METHOD
Write one of the polynomials across the top and the other down the left side.
$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{x^2} & \color{blue}{2x} & \color{blue}{-24} \\ \hline \color{blue}{x} & & & \\ \hline \color{blue}{6} & & & \\ \hline \end{darray} $$Fill in each empty box by multiplying the intersecting terms.
$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{x^2} & \color{blue}{2x} & \color{blue}{-24} \\ \hline \color{blue}{x} & \color{orangered}{x^3} & \color{orangered}{2x^2} & \color{orangered}{-24x} \\ \hline \color{blue}{6} & \color{orangered}{6x^2} & \color{orangered}{12x} & \color{orangered}{-144} \\ \hline \end{darray} $$Combine like terms:
$$ x^3 + 2x^2 + 6x^2-24x + 12x-144 = \\ x^3+8x^2-12x-144 $$