| $$ \begin{aligned}(2x^2+7x)^2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4x^4+28x^3+49x^2\end{aligned} $$ | |
| ① | Find $ \left(2x^2+7x\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^2 } $ and $ B = \color{red}{ 7x }$. $$ \begin{aligned}\left(2x^2+7x\right)^2 = \color{blue}{\left( 2x^2 \right)^2} +2 \cdot 2x^2 \cdot 7x + \color{red}{\left( 7x \right)^2} = 4x^4+28x^3+49x^2\end{aligned} $$ |