Question
Answer
$$(2+4i)\cdot(3+5i)=20i^2+22i+6$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(2+4i)\cdot(3+5i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}6+10i+12i+20i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}20i^2+22i+6\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{2+4i}\right) $ by each term in $ \left( 3+5i\right) $. $$ \left( \color{blue}{2+4i}\right) \cdot \left( 3+5i\right) = 6+10i+12i+20i^2 $$ |
| ② | Combine like terms: $$ 6+ \color{blue}{10i} + \color{blue}{12i} +20i^2 = 20i^2+ \color{blue}{22i} +6 $$ |
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