Question
Answer
$$(4+i\cdot5)\cdot(7-i\cdot3)=-15i^2+23i+28$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}(4+i\cdot5)\cdot(7-i\cdot3)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}28-12i+35i-15i^2 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-15i^2+23i+28\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{4+5i}\right) $ by each term in $ \left( 7-3i\right) $. $$ \left( \color{blue}{4+5i}\right) \cdot \left( 7-3i\right) = 28-12i+35i-15i^2 $$ |
| ② | Combine like terms: $$ 28 \color{blue}{-12i} + \color{blue}{35i} -15i^2 = -15i^2+ \color{blue}{23i} +28 $$ |
This page was created using
Complex Expression calculator