Question
Answer
$$(-3+5i)\cdot(-7-6i)=-30i^2-17i+21$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-3+5i)\cdot(-7-6i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}21+18i-35i-30i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-30i^2-17i+21\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-3+5i}\right) $ by each term in $ \left( -7-6i\right) $. $$ \left( \color{blue}{-3+5i}\right) \cdot \left( -7-6i\right) = 21+18i-35i-30i^2 $$ |
| ② | Combine like terms: $$ 21+ \color{blue}{18i} \color{blue}{-35i} -30i^2 = -30i^2 \color{blue}{-17i} +21 $$ |
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