Question
Answer
$$-8i\cdot(2+7i)+30i=14i+56$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}-8i\cdot(2+7i)+30i& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-(16i+56i^2)+30i \xlongequal{ } \\[1 em] & \xlongequal{ }-(16i-56)+30i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-16i+56+30i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}14i+56\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{8i} $ by $ \left( 2+7i\right) $ $$ \color{blue}{8i} \cdot \left( 2+7i\right) = 16i+56i^2 $$ |
| ② | Remove the parentheses by changing the sign of each term within them. $$ - \left(16i-56 \right) = -16i+56 $$ |
| ③ | Combine like terms: $$ \color{blue}{-16i} +56+ \color{blue}{30i} = \color{blue}{14i} +56 $$ |
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