Multiply polynomial $ \, \color{blue}{ x+8 } \, $ by $ \, \color{orangered}{ x^2+4x+9 }$.

$$ \left( \color{blue}{x+8} \right) \cdot \left( \color{orangered}{x^2+4x+9} \right) = x^3+12x^2+41x+72 $$

We can multiply polynomials by using a GRID METHOD

Write one of the polynomials across the top and the other down the left side.

$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{x^2} & \color{blue}{4x} & \color{blue}{9} \\ \hline \color{blue}{x} & & & \\ \hline \color{blue}{8} & & & \\ \hline \end{darray} $$

Fill in each empty box by multiplying the intersecting terms.

$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{x^2} & \color{blue}{4x} & \color{blue}{9} \\ \hline \color{blue}{x} & \color{orangered}{x^3} & \color{orangered}{4x^2} & \color{orangered}{9x} \\ \hline \color{blue}{8} & \color{orangered}{8x^2} & \color{orangered}{32x} & \color{orangered}{72} \\ \hline \end{darray} $$

Combine like terms:

$$ x^3 + 4x^2 + 8x^2 + 9x + 32x + 72 = \\ x^3+12x^2+41x+72 $$

Polynomial Operations Calculator