| $$ \begin{aligned}\frac{1}{4}\sqrt{64}\sqrt{5}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2\sqrt{5}\end{aligned} $$ | |
| ① | $$ \frac{ 1 }{ 4 } \sqrt{ 320 } =
\frac{ 1 }{ 4 } \sqrt{ 8 ^2 \cdot 5 } =
\frac{ 1 }{ 4 } \sqrt{ 8 ^2 } \, \sqrt{ 5 } =
\frac{ 1 }{ 4 } \cdot 8 \sqrt{ 5 } =
2 \sqrt{ 5 } $$ |