Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{-9}{\sqrt{6}-3}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{-9}{\sqrt{6}-3}\frac{\sqrt{6}+3}{\sqrt{6}+3} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{-9\sqrt{6}-27}{6+3\sqrt{6}-3\sqrt{6}-9} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{-9\sqrt{6}-27}{-3} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}\frac{9\sqrt{6}+27}{3}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{6} + 3} $$. |
② | Multiply in a numerator. $$ \color{blue}{ -9 } \cdot \left( \sqrt{6} + 3\right) = \color{blue}{-9} \cdot \sqrt{6}\color{blue}{-9} \cdot3 = \\ = - 9 \sqrt{6}-27 $$ Simplify denominator. $$ \color{blue}{ \left( \sqrt{6}-3\right) } \cdot \left( \sqrt{6} + 3\right) = \color{blue}{ \sqrt{6}} \cdot \sqrt{6}+\color{blue}{ \sqrt{6}} \cdot3\color{blue}{-3} \cdot \sqrt{6}\color{blue}{-3} \cdot3 = \\ = 6 + 3 \sqrt{6}- 3 \sqrt{6}-9 $$ |
③ | Simplify numerator and denominator |
④ | Multiply both numerator and denominator by -1. |