Question
Answer
$$(8+8i)\cdot(-3+9i)=72i^2+48i-24$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(8+8i)\cdot(-3+9i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-24+72i-24i+72i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}72i^2+48i-24\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{8+8i}\right) $ by each term in $ \left( -3+9i\right) $. $$ \left( \color{blue}{8+8i}\right) \cdot \left( -3+9i\right) = -24+72i-24i+72i^2 $$ |
| ② | Combine like terms: $$ -24+ \color{blue}{72i} \color{blue}{-24i} +72i^2 = 72i^2+ \color{blue}{48i} -24 $$ |
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