Tap the blue circles to see an explanation.
$$ \begin{aligned}(1+8i)\cdot(-3-2i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-3-2i-24i-16i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-16i^2-26i-3\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{1+8i}\right) $ by each term in $ \left( -3-2i\right) $. $$ \left( \color{blue}{1+8i}\right) \cdot \left( -3-2i\right) = -3-2i-24i-16i^2 $$ |
② | Combine like terms: $$ -3 \color{blue}{-2i} \color{blue}{-24i} -16i^2 = -16i^2 \color{blue}{-26i} -3 $$ |