Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{\sqrt{2}}{3+\sqrt{7}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{\sqrt{2}}{3+\sqrt{7}}\frac{3-\sqrt{7}}{3-\sqrt{7}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{3\sqrt{2}-\sqrt{14}}{9-3\sqrt{7}+3\sqrt{7}-7} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{3\sqrt{2}-\sqrt{14}}{2}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 3- \sqrt{7}} $$. |
② | Multiply in a numerator. $$ \color{blue}{ \sqrt{2} } \cdot \left( 3- \sqrt{7}\right) = \color{blue}{ \sqrt{2}} \cdot3+\color{blue}{ \sqrt{2}} \cdot- \sqrt{7} = \\ = 3 \sqrt{2}- \sqrt{14} $$ Simplify denominator. $$ \color{blue}{ \left( 3 + \sqrt{7}\right) } \cdot \left( 3- \sqrt{7}\right) = \color{blue}{3} \cdot3+\color{blue}{3} \cdot- \sqrt{7}+\color{blue}{ \sqrt{7}} \cdot3+\color{blue}{ \sqrt{7}} \cdot- \sqrt{7} = \\ = 9- 3 \sqrt{7} + 3 \sqrt{7}-7 $$ |
③ | Simplify numerator and denominator |