Question
Answer
$$(4-3i)\cdot(5-5i)=15i^2-35i+20$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(4-3i)\cdot(5-5i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}20-20i-15i+15i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}15i^2-35i+20\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{4-3i}\right) $ by each term in $ \left( 5-5i\right) $. $$ \left( \color{blue}{4-3i}\right) \cdot \left( 5-5i\right) = 20-20i-15i+15i^2 $$ |
| ② | Combine like terms: $$ 20 \color{blue}{-20i} \color{blue}{-15i} +15i^2 = 15i^2 \color{blue}{-35i} +20 $$ |
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