Question
Answer
$$(7+i)\cdot(9-6i)=-6i^2-33i+63$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(7+i)\cdot(9-6i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}63-42i+9i-6i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-6i^2-33i+63\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{7+i}\right) $ by each term in $ \left( 9-6i\right) $. $$ \left( \color{blue}{7+i}\right) \cdot \left( 9-6i\right) = 63-42i+9i-6i^2 $$ |
| ② | Combine like terms: $$ 63 \color{blue}{-42i} + \color{blue}{9i} -6i^2 = -6i^2 \color{blue}{-33i} +63 $$ |
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