Question
Multiply polynomial $ \, \color{blue}{ 2x^2+9x-5 } \, $ by $ \, \color{orangered}{ x-3 }$.
Answer
$$ \left( \color{blue}{2x^2+9x-5} \right) \cdot \left( \color{orangered}{x-3} \right) = 2x^3+3x^2-32x+15 $$
Explanation
We can multiply polynomials by using a GRID METHOD
Write one of the polynomials across the top and the other down the left side.
$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{2x^2} & \color{blue}{9x} & \color{blue}{-5} \\ \hline \color{blue}{x} & & & \\ \hline \color{blue}{-3} & & & \\ \hline \end{darray} $$Fill in each empty box by multiplying the intersecting terms.
$$ \begin{darray}{|c|c|c|c|}\hline & \color{blue}{2x^2} & \color{blue}{9x} & \color{blue}{-5} \\ \hline \color{blue}{x} & \color{orangered}{2x^3} & \color{orangered}{9x^2} & \color{orangered}{-5x} \\ \hline \color{blue}{-3} & \color{orangered}{-6x^2} & \color{orangered}{-27x} & \color{orangered}{15} \\ \hline \end{darray} $$Combine like terms:
$$ 2x^3 + 9x^2-6x^2-5x-27x + 15 = \\ 2x^3+3x^2-32x+15 $$This page was created using
Polynomial Operations Calculator