| $$ \begin{aligned}i^3+i^3& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2i^3\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{i^3} + \color{blue}{i^3} = \color{blue}{2i^3} $$ |