Question
Answer
$$(-8+10i)\cdot(-9+3i)=30i^2-114i+72$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-8+10i)\cdot(-9+3i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}72-24i-90i+30i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}30i^2-114i+72\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-8+10i}\right) $ by each term in $ \left( -9+3i\right) $. $$ \left( \color{blue}{-8+10i}\right) \cdot \left( -9+3i\right) = 72-24i-90i+30i^2 $$ |
| ② | Combine like terms: $$ 72 \color{blue}{-24i} \color{blue}{-90i} +30i^2 = 30i^2 \color{blue}{-114i} +72 $$ |
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