Question
Multiply polynomial $ \, \color{blue}{ x+9 } \, $ by $ \, \color{orangered}{ x^2+9x }$.
Answer
$$ \left( \color{blue}{x+9} \right) \cdot \left( \color{orangered}{x^2+9x} \right) = x^3+18x^2+81x $$
Explanation
In this example we are multiplying two binomials so FOIL method can be used.
$$ \begin{aligned} \left( \color{blue}{ x+9}\right) \cdot \left( \color{orangered}{ x^2+9x}\right) &= \underbrace{ \color{blue}{x} \cdot \color{orangered}{x^2} }_{\text{FIRST}} + \underbrace{ \color{blue}{x} \cdot \color{orangered}{9x} }_{\text{OUTER}} + \underbrace{ \color{blue}{9} \cdot \color{orangered}{x^2} }_{\text{INNER}} + \underbrace{ \color{blue}{9} \cdot \color{orangered}{9x} }_{\text{LAST}} = \\ &= x^3 + 9x^2 + 9x^2 + 81x = \\ &= x^3 + 9x^2 + 9x^2 + 81x = \\ &= x^3+18x^2+81x; \end{aligned} $$This page was created using
Polynomial Operations Calculator