Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{1-\sqrt{5}}{\sqrt{8}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{1-\sqrt{5}}{\sqrt{8}}\frac{\sqrt{8}}{\sqrt{8}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{2\sqrt{2}-2\sqrt{10}}{8} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{\sqrt{2}-\sqrt{10}}{4}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{8}} $$. |
② | Multiply in a numerator. $$ \color{blue}{ \left( 1- \sqrt{5}\right) } \cdot \sqrt{8} = \color{blue}{1} \cdot \sqrt{8}\color{blue}{- \sqrt{5}} \cdot \sqrt{8} = \\ = 2 \sqrt{2}- 2 \sqrt{10} $$ Simplify denominator. $$ \color{blue}{ \sqrt{8} } \cdot \sqrt{8} = 8 $$ |
③ | Divide both numerator and denominator by 2. |