Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{3}{5+\sqrt{11}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{3}{5+\sqrt{11}}\frac{5-\sqrt{11}}{5-\sqrt{11}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{15-3\sqrt{11}}{25-5\sqrt{11}+5\sqrt{11}-11} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{15-3\sqrt{11}}{14}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 5- \sqrt{11}} $$. |
② | Multiply in a numerator. $$ \color{blue}{ 3 } \cdot \left( 5- \sqrt{11}\right) = \color{blue}{3} \cdot5+\color{blue}{3} \cdot- \sqrt{11} = \\ = 15- 3 \sqrt{11} $$ Simplify denominator. $$ \color{blue}{ \left( 5 + \sqrt{11}\right) } \cdot \left( 5- \sqrt{11}\right) = \color{blue}{5} \cdot5+\color{blue}{5} \cdot- \sqrt{11}+\color{blue}{ \sqrt{11}} \cdot5+\color{blue}{ \sqrt{11}} \cdot- \sqrt{11} = \\ = 25- 5 \sqrt{11} + 5 \sqrt{11}-11 $$ |
③ | Simplify numerator and denominator |