Question
Answer
$$(-8i-8)\cdot(9-7i)=56i^2-16i-72$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-8i-8)\cdot(9-7i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-72i+56i^2-72+56i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}56i^2-16i-72\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-8i-8}\right) $ by each term in $ \left( 9-7i\right) $. $$ \left( \color{blue}{-8i-8}\right) \cdot \left( 9-7i\right) = -72i+56i^2-72+56i $$ |
| ② | Combine like terms: $$ \color{blue}{-72i} +56i^2-72+ \color{blue}{56i} = 56i^2 \color{blue}{-16i} -72 $$ |
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