Question
Answer
$$(-1+2i)\cdot(-2+10i)=20i^2-14i+2$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-1+2i)\cdot(-2+10i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2-10i-4i+20i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}20i^2-14i+2\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-1+2i}\right) $ by each term in $ \left( -2+10i\right) $. $$ \left( \color{blue}{-1+2i}\right) \cdot \left( -2+10i\right) = 2-10i-4i+20i^2 $$ |
| ② | Combine like terms: $$ 2 \color{blue}{-10i} \color{blue}{-4i} +20i^2 = 20i^2 \color{blue}{-14i} +2 $$ |
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