| $$ \begin{aligned}-i^{13}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-i\end{aligned} $$ | |
| ① | $$ -i^{13} = - i^{4 \cdot 3 + 1} =
- \left( i^4 \right)^{ 3 } \cdot i^1 =
- 1^{ 3 } \cdot i =
- i $$ |