Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{17}{2+\sqrt{13}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{17}{2+\sqrt{13}}\frac{2-\sqrt{13}}{2-\sqrt{13}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{34-17\sqrt{13}}{4-2\sqrt{13}+2\sqrt{13}-13} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{34-17\sqrt{13}}{-9} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}\frac{-34+17\sqrt{13}}{9}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 2- \sqrt{13}} $$. |
② | Multiply in a numerator. $$ \color{blue}{ 17 } \cdot \left( 2- \sqrt{13}\right) = \color{blue}{17} \cdot2+\color{blue}{17} \cdot- \sqrt{13} = \\ = 34- 17 \sqrt{13} $$ Simplify denominator. $$ \color{blue}{ \left( 2 + \sqrt{13}\right) } \cdot \left( 2- \sqrt{13}\right) = \color{blue}{2} \cdot2+\color{blue}{2} \cdot- \sqrt{13}+\color{blue}{ \sqrt{13}} \cdot2+\color{blue}{ \sqrt{13}} \cdot- \sqrt{13} = \\ = 4- 2 \sqrt{13} + 2 \sqrt{13}-13 $$ |
③ | Simplify numerator and denominator |
④ | Multiply both numerator and denominator by -1. |