Question
Answer
$$(3-5i)\cdot(2+9i)=-45i^2+17i+6$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(3-5i)\cdot(2+9i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}6+27i-10i-45i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-45i^2+17i+6\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{3-5i}\right) $ by each term in $ \left( 2+9i\right) $. $$ \left( \color{blue}{3-5i}\right) \cdot \left( 2+9i\right) = 6+27i-10i-45i^2 $$ |
| ② | Combine like terms: $$ 6+ \color{blue}{27i} \color{blue}{-10i} -45i^2 = -45i^2+ \color{blue}{17i} +6 $$ |
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