Question
Answer
$$(4-3i)\cdot(-5+4i)=-12i^2+31i-20$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(4-3i)\cdot(-5+4i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-20+16i+15i-12i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-12i^2+31i-20\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{4-3i}\right) $ by each term in $ \left( -5+4i\right) $. $$ \left( \color{blue}{4-3i}\right) \cdot \left( -5+4i\right) = -20+16i+15i-12i^2 $$ |
| ② | Combine like terms: $$ -20+ \color{blue}{16i} + \color{blue}{15i} -12i^2 = -12i^2+ \color{blue}{31i} -20 $$ |
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