Multiply polynomial $ \, \color{blue}{ 9x+7 } \, $ by $ \, \color{orangered}{ 9x+7 }$.

$$ \left( \color{blue}{9x+7} \right) \cdot \left( \color{orangered}{9x+7} \right) = 81x^2+126x+49 $$

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

$$ \begin{aligned} \left( \color{blue}{ 9x+7}\right) \cdot \left( \color{orangered}{ 9x+7}\right) &= \underbrace{ \color{blue}{9x} \cdot \color{orangered}{9x} }_{\text{FIRST}} + \underbrace{ \color{blue}{9x} \cdot \color{orangered}{7} }_{\text{OUTER}} + \underbrace{ \color{blue}{7} \cdot \color{orangered}{9x} }_{\text{INNER}} + \underbrace{ \color{blue}{7} \cdot \color{orangered}{7} }_{\text{LAST}} = \\ &= 81x^2 + 63x + 63x + 49 = \\ &= 81x^2 + 63x + 63x + 49 = \\ &= 81x^2+126x+49; \end{aligned} $$

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