Question
Answer
$$3\cdot(5-4i)-(15-7i)=-5i$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}3\cdot(5-4i)-(15-7i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}15-12i-(15-7i) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}15-12i-15+7i \xlongequal{ } \\[1 em] & \xlongequal{ } \cancel{15}-12i -\cancel{15}+7i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-5i\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{3} $ by $ \left( 5-4i\right) $ $$ \color{blue}{3} \cdot \left( 5-4i\right) = 15-12i $$ |
| ② | Remove the parentheses by changing the sign of each term within them. $$ - \left( 15-7i \right) = -15+7i $$ |
| ③ | Combine like terms: $$ \, \color{blue}{ \cancel{15}} \, \color{green}{-12i} \, \color{blue}{ -\cancel{15}} \,+ \color{green}{7i} = \color{green}{-5i} $$ |
This page was created using
Complex Expression calculator