Question
Answer
$$\dfrac{2\sqrt{7}}{4+\sqrt{6}}=\dfrac{4\sqrt{7}-\sqrt{42}}{5}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{2\sqrt{7}}{4+\sqrt{6}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{2\sqrt{7}}{4+\sqrt{6}}\frac{4-\sqrt{6}}{4-\sqrt{6}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{8\sqrt{7}-2\sqrt{42}}{16-4\sqrt{6}+4\sqrt{6}-6} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{8\sqrt{7}-2\sqrt{42}}{10} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}\frac{4\sqrt{7}-\sqrt{42}}{5}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 4- \sqrt{6}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 2 \sqrt{7} } \cdot \left( 4- \sqrt{6}\right) = \color{blue}{ 2 \sqrt{7}} \cdot4+\color{blue}{ 2 \sqrt{7}} \cdot- \sqrt{6} = \\ = 8 \sqrt{7}- 2 \sqrt{42} $$ Simplify denominator. $$ \color{blue}{ \left( 4 + \sqrt{6}\right) } \cdot \left( 4- \sqrt{6}\right) = \color{blue}{4} \cdot4+\color{blue}{4} \cdot- \sqrt{6}+\color{blue}{ \sqrt{6}} \cdot4+\color{blue}{ \sqrt{6}} \cdot- \sqrt{6} = \\ = 16- 4 \sqrt{6} + 4 \sqrt{6}-6 $$ |
| ③ | Simplify numerator and denominator |
| ④ | Divide both numerator and denominator by 2. |
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