Question
Answer
$$(5+8i)\cdot(-8+2i)=16i^2-54i-40$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(5+8i)\cdot(-8+2i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-40+10i-64i+16i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}16i^2-54i-40\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{5+8i}\right) $ by each term in $ \left( -8+2i\right) $. $$ \left( \color{blue}{5+8i}\right) \cdot \left( -8+2i\right) = -40+10i-64i+16i^2 $$ |
| ② | Combine like terms: $$ -40+ \color{blue}{10i} \color{blue}{-64i} +16i^2 = 16i^2 \color{blue}{-54i} -40 $$ |
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