Question
Answer
$$(-1-2i)\cdot(6+5i)=-10i^2-17i-6$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-1-2i)\cdot(6+5i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-6-5i-12i-10i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-10i^2-17i-6\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-1-2i}\right) $ by each term in $ \left( 6+5i\right) $. $$ \left( \color{blue}{-1-2i}\right) \cdot \left( 6+5i\right) = -6-5i-12i-10i^2 $$ |
| ② | Combine like terms: $$ -6 \color{blue}{-5i} \color{blue}{-12i} -10i^2 = -10i^2 \color{blue}{-17i} -6 $$ |
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