Tap the blue circles to see an explanation.
$$ \begin{aligned}(2x-7)(2x+7)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4x^2+14x-14x-49 \xlongequal{ } \\[1 em] & \xlongequal{ }4x^2+ \cancel{14x} -\cancel{14x}-49 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}4x^2-49\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{2x-7}\right) $ by each term in $ \left( 2x+7\right) $. $$ \left( \color{blue}{2x-7}\right) \cdot \left( 2x+7\right) = 4x^2+ \cancel{14x} -\cancel{14x}-49 $$ |
② | Combine like terms: $$ 4x^2+ \, \color{blue}{ \cancel{14x}} \, \, \color{blue}{ -\cancel{14x}} \,-49 = 4x^2-49 $$ |