Question
Answer
$$(-5+9i)(-6i-4)=-54i^2-6i+20$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-5+9i)(-6i-4)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}30i+20-54i^2-36i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-54i^2-6i+20\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-5+9i}\right) $ by each term in $ \left( -6i-4\right) $. $$ \left( \color{blue}{-5+9i}\right) \cdot \left( -6i-4\right) = 30i+20-54i^2-36i $$ |
| ② | Combine like terms: $$ \color{blue}{30i} +20-54i^2 \color{blue}{-36i} = -54i^2 \color{blue}{-6i} +20 $$ |
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