Multiply polynomial $ \, \color{blue}{ x+4 } \, $ by $ \, \color{orangered}{ 2x+5 }$.

$$ \left( \color{blue}{x+4} \right) \cdot \left( \color{orangered}{2x+5} \right) = 2x^2+13x+20 $$

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

$$ \begin{aligned} \left( \color{blue}{ x+4}\right) \cdot \left( \color{orangered}{ 2x+5}\right) &= \underbrace{ \color{blue}{x} \cdot \color{orangered}{2x} }_{\text{FIRST}} + \underbrace{ \color{blue}{x} \cdot \color{orangered}{5} }_{\text{OUTER}} + \underbrace{ \color{blue}{4} \cdot \color{orangered}{2x} }_{\text{INNER}} + \underbrace{ \color{blue}{4} \cdot \color{orangered}{5} }_{\text{LAST}} = \\ &= 2x^2 + 5x + 8x + 20 = \\ &= 2x^2 + 5x + 8x + 20 = \\ &= 2x^2+13x+20; \end{aligned} $$

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