Multiply polynomial $ \, \color{blue}{ 5x+9 } \, $ by $ \, \color{orangered}{ 5x+11 }$.

$$ \left( \color{blue}{5x+9} \right) \cdot \left( \color{orangered}{5x+11} \right) = 25x^2+100x+99 $$

In this example we are multiplying two binomials so FOIL method can be used.

$$ \begin{aligned} \left( \color{blue}{ 5x+9}\right) \cdot \left( \color{orangered}{ 5x+11}\right) &= \underbrace{ \color{blue}{5x} \cdot \color{orangered}{5x} }_{\text{FIRST}} + \underbrace{ \color{blue}{5x} \cdot \color{orangered}{11} }_{\text{OUTER}} + \underbrace{ \color{blue}{9} \cdot \color{orangered}{5x} }_{\text{INNER}} + \underbrace{ \color{blue}{9} \cdot \color{orangered}{11} }_{\text{LAST}} = \\ &= 25x^2 + 55x + 45x + 99 = \\ &= 25x^2 + 55x + 45x + 99 = \\ &= 25x^2+100x+99; \end{aligned} $$

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