Question
Answer
$$(-i-5)(8i-1)=-8i^2-39i+5$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-i-5)(8i-1)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-8i^2+i-40i+5 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-8i^2-39i+5\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-i-5}\right) $ by each term in $ \left( 8i-1\right) $. $$ \left( \color{blue}{-i-5}\right) \cdot \left( 8i-1\right) = -8i^2+i-40i+5 $$ |
| ② | Combine like terms: $$ -8i^2+ \color{blue}{i} \color{blue}{-40i} +5 = -8i^2 \color{blue}{-39i} +5 $$ |
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