| $$ \begin{aligned}\sqrt{7}\cdot\sqrt{7}& \xlongequal{ }\sqrt{49} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}7\end{aligned} $$ | |
| ① | The square root of $ 49 $ is $ 7 $. |