Answer
$$(-6+9i)\cdot(3+i)=9i^2+21i-18$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(-6+9i)\cdot(3+i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-18-6i+27i+9i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}9i^2+21i-18\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{-6+9i}\right) $ by each term in $ \left( 3+i\right) $. $$ \left( \color{blue}{-6+9i}\right) \cdot \left( 3+i\right) = -18-6i+27i+9i^2 $$ |
| ② | Combine like terms: $$ -18 \color{blue}{-6i} + \color{blue}{27i} +9i^2 = 9i^2+ \color{blue}{21i} -18 $$ |
This page was created using
Complex Expression calculator