Question
Answer
$$2+3i\cdot(1+3i)=3i-7$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}2+3i\cdot(1+3i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2+3i+9i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}2+3i-9 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}3i-7\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{3i} $ by $ \left( 1+3i\right) $ $$ \color{blue}{3i} \cdot \left( 1+3i\right) = 3i+9i^2 $$ |
| ② | $$ 9i^2 = 9 \cdot (-1) = -9 $$ |
| ③ | Combine like terms: $$ \color{blue}{2} +3i \color{blue}{-9} = 3i \color{blue}{-7} $$ |
This page was created using
Complex Expression calculator