| $$ \begin{aligned}\frac{42}{(2x+8)^2}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{42}{4x^2+32x+64}\end{aligned} $$ | |
| ① | Find $ \left(2x+8\right)^2 $ using formula. $$ (A + B)^2 = \color{blue}{A^2} + 2 \cdot A \cdot B + \color{red}{B^2} $$where $ A = \color{blue}{ 2x } $ and $ B = \color{red}{ 8 }$. $$ \begin{aligned}\left(2x+8\right)^2 = \color{blue}{\left( 2x \right)^2} +2 \cdot 2x \cdot 8 + \color{red}{8^2} = 4x^2+32x+64\end{aligned} $$ |