Question
Answer
$$(-10-9i)\cdot(-3-2i)=18i^2+47i+30$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-10-9i)\cdot(-3-2i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}30+20i+27i+18i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}18i^2+47i+30\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-10-9i}\right) $ by each term in $ \left( -3-2i\right) $. $$ \left( \color{blue}{-10-9i}\right) \cdot \left( -3-2i\right) = 30+20i+27i+18i^2 $$ |
| ② | Combine like terms: $$ 30+ \color{blue}{20i} + \color{blue}{27i} +18i^2 = 18i^2+ \color{blue}{47i} +30 $$ |
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