Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{4}{\sqrt{10}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \frac{ 4 }{\sqrt{ 10 }} \times \frac{ \color{orangered}{\sqrt{ 10 }} }{ \color{orangered}{\sqrt{ 10 }}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{4\sqrt{10}}{10} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}} \frac{ 4 \sqrt{ 10 } : \color{blue}{ 2 } }{ 10 : \color{blue}{ 2 } } \xlongequal{ } \\[1 em] & \xlongequal{ }\frac{2\sqrt{10}}{5}\end{aligned} $$ | |
① | Multiply both top and bottom by $ \color{orangered}{ \sqrt{ 10 }}$. |
② | In denominator we have $ \sqrt{ 10 } \cdot \sqrt{ 10 } = 10 $. |
③ | Divide both the top and bottom numbers by $ \color{blue}{ 2 }$. |