Question
Answer
$$-2-(-7+9i)-(-2-7i)=-2i+7$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}-2-(-7+9i)-(-2-7i)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-2+7-9i-(-2-7i) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-9i+5-(-2-7i) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}-9i+5+2+7i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}-2i+7\end{aligned} $$ | |
| ① | Remove the parentheses by changing the sign of each term within them. $$ - \left( -7+9i \right) = 7-9i $$ |
| ② | Combine like terms: $$ \color{blue}{-2} + \color{blue}{7} -9i = -9i+ \color{blue}{5} $$ |
| ③ | Remove the parentheses by changing the sign of each term within them. $$ - \left( -2-7i \right) = 2+7i $$ |
| ④ | Combine like terms: $$ \color{blue}{-9i} + \color{red}{5} + \color{red}{2} + \color{blue}{7i} = \color{blue}{-2i} + \color{red}{7} $$ |
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