| $$ \begin{aligned}5v\cdot4\cdot3v\cdot9& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}540v^2\end{aligned} $$ | |
| ① | $$ 5 v \cdot 4 \cdot 3 v \cdot 9 = 540 v^{1 + 1} = 540 v^2 $$ |