Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{2}{3\sqrt{5}-6}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{2}{3\sqrt{5}-6}\frac{3\sqrt{5}+6}{3\sqrt{5}+6} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{6\sqrt{5}+12}{45+18\sqrt{5}-18\sqrt{5}-36} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{6\sqrt{5}+12}{9}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 3 \sqrt{5} + 6} $$. |
② | Multiply in a numerator. $$ \color{blue}{ 2 } \cdot \left( 3 \sqrt{5} + 6\right) = \color{blue}{2} \cdot 3 \sqrt{5}+\color{blue}{2} \cdot6 = \\ = 6 \sqrt{5} + 12 $$ Simplify denominator. $$ \color{blue}{ \left( 3 \sqrt{5}-6\right) } \cdot \left( 3 \sqrt{5} + 6\right) = \color{blue}{ 3 \sqrt{5}} \cdot 3 \sqrt{5}+\color{blue}{ 3 \sqrt{5}} \cdot6\color{blue}{-6} \cdot 3 \sqrt{5}\color{blue}{-6} \cdot6 = \\ = 45 + 18 \sqrt{5}- 18 \sqrt{5}-36 $$ |
③ | Simplify numerator and denominator |