| $$ \begin{aligned}\sqrt{3}\cdot(5+\sqrt{3})& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}5\sqrt{3}+3\end{aligned} $$ | |
| ① | $$ \color{blue}{ \sqrt{3} } \cdot \left( 5 + \sqrt{3}\right) = \color{blue}{ \sqrt{3}} \cdot5+\color{blue}{ \sqrt{3}} \cdot \sqrt{3} = \\ = 5 \sqrt{3} + 3 $$ |