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