Question
Answer
$$(8+5i)\cdot(3-4i)=-20i^2-17i+24$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(8+5i)\cdot(3-4i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}24-32i+15i-20i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-20i^2-17i+24\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{8+5i}\right) $ by each term in $ \left( 3-4i\right) $. $$ \left( \color{blue}{8+5i}\right) \cdot \left( 3-4i\right) = 24-32i+15i-20i^2 $$ |
| ② | Combine like terms: $$ 24 \color{blue}{-32i} + \color{blue}{15i} -20i^2 = -20i^2 \color{blue}{-17i} +24 $$ |
This page was created using
Complex Expression calculator