Tap the blue circles to see an explanation.
$$ \begin{aligned}(x-2)(x+2)(x+4)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}(x^2+2x-2x-4)(x+4) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}(x^2-4)(x+4) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}x^3+4x^2-4x-16\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{x-2}\right) $ by each term in $ \left( x+2\right) $. $$ \left( \color{blue}{x-2}\right) \cdot \left( x+2\right) = x^2+ \cancel{2x} -\cancel{2x}-4 $$ |
② | Combine like terms: $$ x^2+ \, \color{blue}{ \cancel{2x}} \, \, \color{blue}{ -\cancel{2x}} \,-4 = x^2-4 $$ |
③ | Multiply each term of $ \left( \color{blue}{x^2-4}\right) $ by each term in $ \left( x+4\right) $. $$ \left( \color{blue}{x^2-4}\right) \cdot \left( x+4\right) = x^3+4x^2-4x-16 $$ |