Question
Answer
$$(5-6i)\cdot(4+8i)=-48i^2+16i+20$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(5-6i)\cdot(4+8i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}20+40i-24i-48i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-48i^2+16i+20\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{5-6i}\right) $ by each term in $ \left( 4+8i\right) $. $$ \left( \color{blue}{5-6i}\right) \cdot \left( 4+8i\right) = 20+40i-24i-48i^2 $$ |
| ② | Combine like terms: $$ 20+ \color{blue}{40i} \color{blue}{-24i} -48i^2 = -48i^2+ \color{blue}{16i} +20 $$ |
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