Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{\sqrt{140}}{\sqrt{21}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{\sqrt{140}}{\sqrt{21}}\frac{\sqrt{21}}{\sqrt{21}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{14\sqrt{15}}{21} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{ 14 \sqrt{ 15 } : \color{blue}{ 7 } } { 21 : \color{blue}{ 7 }} \xlongequal{ } \\[1 em] & \xlongequal{ }\frac{2\sqrt{15}}{3}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{21}} $$. |
② | Multiply in a numerator. $$ \color{blue}{ \sqrt{140} } \cdot \sqrt{21} = 14 \sqrt{15} $$ Simplify denominator. $$ \color{blue}{ \sqrt{21} } \cdot \sqrt{21} = 21 $$ |
③ | Divide numerator and denominator by $ \color{blue}{ 7 } $. |