Question
Answer
$$(-4-7i)\cdot(2+10i)=-70i^2-54i-8$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-4-7i)\cdot(2+10i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-8-40i-14i-70i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-70i^2-54i-8\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-4-7i}\right) $ by each term in $ \left( 2+10i\right) $. $$ \left( \color{blue}{-4-7i}\right) \cdot \left( 2+10i\right) = -8-40i-14i-70i^2 $$ |
| ② | Combine like terms: $$ -8 \color{blue}{-40i} \color{blue}{-14i} -70i^2 = -70i^2 \color{blue}{-54i} -8 $$ |
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