$$ \begin{aligned}\sqrt{3}\cdot\sqrt{10}\sqrt{8}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4\sqrt{15}\end{aligned} $$ | |
① | $$ \sqrt{240} =
\sqrt{ 4 ^2 \cdot 15 } =
\sqrt{ 4 ^2 } \, \sqrt{ 15 } =
4 \sqrt{ 15 }$$ |