Question
Answer
$$\dfrac{15}{\sqrt{10}-\sqrt{2}}=\dfrac{15\sqrt{10}+15\sqrt{2}}{8}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{15}{\sqrt{10}-\sqrt{2}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{15}{\sqrt{10}-\sqrt{2}}\frac{\sqrt{10}+\sqrt{2}}{\sqrt{10}+\sqrt{2}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{15\sqrt{10}+15\sqrt{2}}{10+2\sqrt{5}-2\sqrt{5}-2} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{15\sqrt{10}+15\sqrt{2}}{8}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{10} + \sqrt{2}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 15 } \cdot \left( \sqrt{10} + \sqrt{2}\right) = \color{blue}{15} \cdot \sqrt{10}+\color{blue}{15} \cdot \sqrt{2} = \\ = 15 \sqrt{10} + 15 \sqrt{2} $$ Simplify denominator. $$ \color{blue}{ \left( \sqrt{10}- \sqrt{2}\right) } \cdot \left( \sqrt{10} + \sqrt{2}\right) = \color{blue}{ \sqrt{10}} \cdot \sqrt{10}+\color{blue}{ \sqrt{10}} \cdot \sqrt{2}\color{blue}{- \sqrt{2}} \cdot \sqrt{10}\color{blue}{- \sqrt{2}} \cdot \sqrt{2} = \\ = 10 + 2 \sqrt{5}- 2 \sqrt{5}-2 $$ |
| ③ | Simplify numerator and denominator |
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