Question
Answer
$$(12+8i)\cdot(8-5i)=-40i^2+4i+96$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(12+8i)\cdot(8-5i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}96-60i+64i-40i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-40i^2+4i+96\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{12+8i}\right) $ by each term in $ \left( 8-5i\right) $. $$ \left( \color{blue}{12+8i}\right) \cdot \left( 8-5i\right) = 96-60i+64i-40i^2 $$ |
| ② | Combine like terms: $$ 96 \color{blue}{-60i} + \color{blue}{64i} -40i^2 = -40i^2+ \color{blue}{4i} +96 $$ |
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