Question
Answer
$$\dfrac{2\sqrt{3}}{\sqrt{5}+2\sqrt{6}}=\dfrac{-2\sqrt{15}+12\sqrt{2}}{19}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{2\sqrt{3}}{\sqrt{5}+2\sqrt{6}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{2\sqrt{3}}{\sqrt{5}+2\sqrt{6}}\frac{\sqrt{5}-2\sqrt{6}}{\sqrt{5}-2\sqrt{6}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{2\sqrt{15}-12\sqrt{2}}{5-2\sqrt{30}+2\sqrt{30}-24} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{2\sqrt{15}-12\sqrt{2}}{-19} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}\frac{-2\sqrt{15}+12\sqrt{2}}{19}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{5}- 2 \sqrt{6}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 2 \sqrt{3} } \cdot \left( \sqrt{5}- 2 \sqrt{6}\right) = \color{blue}{ 2 \sqrt{3}} \cdot \sqrt{5}+\color{blue}{ 2 \sqrt{3}} \cdot- 2 \sqrt{6} = \\ = 2 \sqrt{15}- 12 \sqrt{2} $$ Simplify denominator. $$ \color{blue}{ \left( \sqrt{5} + 2 \sqrt{6}\right) } \cdot \left( \sqrt{5}- 2 \sqrt{6}\right) = \color{blue}{ \sqrt{5}} \cdot \sqrt{5}+\color{blue}{ \sqrt{5}} \cdot- 2 \sqrt{6}+\color{blue}{ 2 \sqrt{6}} \cdot \sqrt{5}+\color{blue}{ 2 \sqrt{6}} \cdot- 2 \sqrt{6} = \\ = 5- 2 \sqrt{30} + 2 \sqrt{30}-24 $$ |
| ③ | Simplify numerator and denominator |
| ④ | Multiply both numerator and denominator by -1. |
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