Question
Answer
$$\dfrac{2}{2\sqrt{5}+2\sqrt{3}}=\dfrac{\sqrt{5}-\sqrt{3}}{2}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{2}{2\sqrt{5}+2\sqrt{3}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{2}{2\sqrt{5}+2\sqrt{3}}\frac{2\sqrt{5}-2\sqrt{3}}{2\sqrt{5}-2\sqrt{3}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{4\sqrt{5}-4\sqrt{3}}{20-4\sqrt{15}+4\sqrt{15}-12} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{4\sqrt{5}-4\sqrt{3}}{8} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}\frac{\sqrt{5}-\sqrt{3}}{2}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 2 \sqrt{5}- 2 \sqrt{3}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 2 } \cdot \left( 2 \sqrt{5}- 2 \sqrt{3}\right) = \color{blue}{2} \cdot 2 \sqrt{5}+\color{blue}{2} \cdot- 2 \sqrt{3} = \\ = 4 \sqrt{5}- 4 \sqrt{3} $$ Simplify denominator. $$ \color{blue}{ \left( 2 \sqrt{5} + 2 \sqrt{3}\right) } \cdot \left( 2 \sqrt{5}- 2 \sqrt{3}\right) = \color{blue}{ 2 \sqrt{5}} \cdot 2 \sqrt{5}+\color{blue}{ 2 \sqrt{5}} \cdot- 2 \sqrt{3}+\color{blue}{ 2 \sqrt{3}} \cdot 2 \sqrt{5}+\color{blue}{ 2 \sqrt{3}} \cdot- 2 \sqrt{3} = \\ = 20- 4 \sqrt{15} + 4 \sqrt{15}-12 $$ |
| ③ | Simplify numerator and denominator |
| ④ | Divide both numerator and denominator by 4. |
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