Question
Answer
$$(1+6i)\cdot(-7+4i)=24i^2-38i-7$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(1+6i)\cdot(-7+4i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-7+4i-42i+24i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}24i^2-38i-7\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{1+6i}\right) $ by each term in $ \left( -7+4i\right) $. $$ \left( \color{blue}{1+6i}\right) \cdot \left( -7+4i\right) = -7+4i-42i+24i^2 $$ |
| ② | Combine like terms: $$ -7+ \color{blue}{4i} \color{blue}{-42i} +24i^2 = 24i^2 \color{blue}{-38i} -7 $$ |
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