Tap the blue circles to see an explanation.
$$ \begin{aligned}(3x-2)(3x+2)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}9x^2+6x-6x-4 \xlongequal{ } \\[1 em] & \xlongequal{ }9x^2+ \cancel{6x} -\cancel{6x}-4 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}9x^2-4\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{3x-2}\right) $ by each term in $ \left( 3x+2\right) $. $$ \left( \color{blue}{3x-2}\right) \cdot \left( 3x+2\right) = 9x^2+ \cancel{6x} -\cancel{6x}-4 $$ |
② | Combine like terms: $$ 9x^2+ \, \color{blue}{ \cancel{6x}} \, \, \color{blue}{ -\cancel{6x}} \,-4 = 9x^2-4 $$ |