Question
Answer
$$(1+3i)\cdot(-11+10i)=30i^2-23i-11$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(1+3i)\cdot(-11+10i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-11+10i-33i+30i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}30i^2-23i-11\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{1+3i}\right) $ by each term in $ \left( -11+10i\right) $. $$ \left( \color{blue}{1+3i}\right) \cdot \left( -11+10i\right) = -11+10i-33i+30i^2 $$ |
| ② | Combine like terms: $$ -11+ \color{blue}{10i} \color{blue}{-33i} +30i^2 = 30i^2 \color{blue}{-23i} -11 $$ |
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