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

$$ \begin{aligned} \left( \color{blue}{ 2x-9}\right) \cdot \left( \color{orangered}{ 2x+6}\right) &= \underbrace{ \color{blue}{2x} \cdot \color{orangered}{2x} }_{\text{FIRST}} + \underbrace{ \color{blue}{2x} \cdot \color{orangered}{6} }_{\text{OUTER}} + \underbrace{ \left( \color{blue}{-9} \right) \cdot \color{orangered}{2x} }_{\text{INNER}} + \underbrace{ \left( \color{blue}{-9} \right) \cdot \color{orangered}{6} }_{\text{LAST}} = \\ &= 4x^2 + 12x + \left( -18x\right) + \left( -54\right) = \\ &= 4x^2 + 12x + \left( -18x\right) + \left( -54\right) = \\ &= 4x^2-6x-54; \end{aligned} $$

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