Question
Answer
$$-i\cdot(5-1)+2i(i+6)=8i-2$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}-i\cdot(5-1)+2i(i+6)& \xlongequal{ }-i\cdot4+2i(i+6) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-i\cdot4+2i^2+12i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}-i\cdot4-2+12i \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}8i-2\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{2i} $ by $ \left( i+6\right) $ $$ \color{blue}{2i} \cdot \left( i+6\right) = 2i^2+12i $$ |
| ② | $$ 2i^2 = 2 \cdot (-1) = -2 $$ |
| ③ | Combine like terms: $$ \color{blue}{-4i} -2+ \color{blue}{12i} = \color{blue}{8i} -2 $$ |
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