| $$ \begin{aligned}\sqrt{\frac{9}{25}}& \xlongequal{ }\frac{1}{5}\sqrt{9} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{3}{5}\end{aligned} $$ | |
| ① | $$ \frac{ 1 }{ 5 } \sqrt{ 9 } = \frac{ 1 }{ 5 } \cdot 3 = \frac{ 3 }{ 5 } $$ |