Tap the blue circles to see an explanation.
| $$ \begin{aligned}(3-yi)^2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}9-6iy+i^2y^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}i^2y^2-6iy+9\end{aligned} $$ | |
| ① | Find $ \left(3-iy\right)^2 $ using formula. $$ (A - B)^2 = \color{blue}{A^2} - 2 \cdot A \cdot B + \color{red}{B^2} $$where $ A = \color{blue}{ 3 } $ and $ B = \color{red}{ iy }$. $$ \begin{aligned}\left(3-iy\right)^2 = \color{blue}{3^2} -2 \cdot 3 \cdot iy + \color{red}{\left( iy \right)^2} = 9-6iy+i^2y^2\end{aligned} $$ |
| ② | Combine like terms: $$ i^2y^2-6iy+9 = i^2y^2-6iy+9 $$ |