Tap the blue circles to see an explanation.
| $$ \begin{aligned}(6-2i)\cdot(6+2i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}36+12i-12i-4i^2 \xlongequal{ } \\[1 em] & \xlongequal{ }36+ \cancel{12i} -\cancel{12i}-4i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-4i^2+36\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{6-2i}\right) $ by each term in $ \left( 6+2i\right) $. $$ \left( \color{blue}{6-2i}\right) \cdot \left( 6+2i\right) = 36+ \cancel{12i} -\cancel{12i}-4i^2 $$ |
| ② | Combine like terms: $$ 36+ \, \color{blue}{ \cancel{12i}} \, \, \color{blue}{ -\cancel{12i}} \,-4i^2 = -4i^2+36 $$ |