Question
Answer
$$\dfrac{2-\sqrt{8}}{3+\sqrt{2}}=\dfrac{10-8\sqrt{2}}{7}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{2-\sqrt{8}}{3+\sqrt{2}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{2-\sqrt{8}}{3+\sqrt{2}}\frac{3-\sqrt{2}}{3-\sqrt{2}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{6-2\sqrt{2}-6\sqrt{2}+4}{9-3\sqrt{2}+3\sqrt{2}-2} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{10-8\sqrt{2}}{7}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 3- \sqrt{2}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ \left( 2- \sqrt{8}\right) } \cdot \left( 3- \sqrt{2}\right) = \color{blue}{2} \cdot3+\color{blue}{2} \cdot- \sqrt{2}\color{blue}{- \sqrt{8}} \cdot3\color{blue}{- \sqrt{8}} \cdot- \sqrt{2} = \\ = 6- 2 \sqrt{2}- 6 \sqrt{2} + 4 $$ Simplify denominator. $$ \color{blue}{ \left( 3 + \sqrt{2}\right) } \cdot \left( 3- \sqrt{2}\right) = \color{blue}{3} \cdot3+\color{blue}{3} \cdot- \sqrt{2}+\color{blue}{ \sqrt{2}} \cdot3+\color{blue}{ \sqrt{2}} \cdot- \sqrt{2} = \\ = 9- 3 \sqrt{2} + 3 \sqrt{2}-2 $$ |
| ③ | Simplify numerator and denominator |
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