Question
Answer
$$(8+7i)\cdot(2+8i)=56i^2+78i+16$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(8+7i)\cdot(2+8i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}16+64i+14i+56i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}56i^2+78i+16\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{8+7i}\right) $ by each term in $ \left( 2+8i\right) $. $$ \left( \color{blue}{8+7i}\right) \cdot \left( 2+8i\right) = 16+64i+14i+56i^2 $$ |
| ② | Combine like terms: $$ 16+ \color{blue}{64i} + \color{blue}{14i} +56i^2 = 56i^2+ \color{blue}{78i} +16 $$ |
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