Question
Answer
$$\dfrac{8}{-\sqrt{15}+\sqrt{2}}=\dfrac{-8\sqrt{15}-8\sqrt{2}}{13}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{8}{-\sqrt{15}+\sqrt{2}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{8}{-\sqrt{15}+\sqrt{2}}\frac{-\sqrt{15}-\sqrt{2}}{-\sqrt{15}-\sqrt{2}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{-8\sqrt{15}-8\sqrt{2}}{15+\sqrt{30}-\sqrt{30}-2} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{-8\sqrt{15}-8\sqrt{2}}{13}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ - \sqrt{15}- \sqrt{2}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 8 } \cdot \left( - \sqrt{15}- \sqrt{2}\right) = \color{blue}{8} \cdot- \sqrt{15}+\color{blue}{8} \cdot- \sqrt{2} = \\ = - 8 \sqrt{15}- 8 \sqrt{2} $$ Simplify denominator. $$ \color{blue}{ \left( - \sqrt{15} + \sqrt{2}\right) } \cdot \left( - \sqrt{15}- \sqrt{2}\right) = \color{blue}{- \sqrt{15}} \cdot- \sqrt{15}\color{blue}{- \sqrt{15}} \cdot- \sqrt{2}+\color{blue}{ \sqrt{2}} \cdot- \sqrt{15}+\color{blue}{ \sqrt{2}} \cdot- \sqrt{2} = \\ = 15 + \sqrt{30}- \sqrt{30}-2 $$ |
| ③ | Simplify numerator and denominator |
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