Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{9}{\sqrt{15}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \frac{ 9 }{\sqrt{ 15 }} \times \frac{ \color{orangered}{\sqrt{ 15 }} }{ \color{orangered}{\sqrt{ 15 }}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{9\sqrt{15}}{15} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}} \frac{ 9 \sqrt{ 15 } : \color{blue}{ 3 } }{ 15 : \color{blue}{ 3 } } \xlongequal{ } \\[1 em] & \xlongequal{ }\frac{3\sqrt{15}}{5}\end{aligned} $$ | |
① | Multiply both top and bottom by $ \color{orangered}{ \sqrt{ 15 }}$. |
② | In denominator we have $ \sqrt{ 15 } \cdot \sqrt{ 15 } = 15 $. |
③ | Divide both the top and bottom numbers by $ \color{blue}{ 3 }$. |