Tap the blue circles to see an explanation.
$$ \begin{aligned}\frac{7+4\sqrt{5}}{\sqrt{5}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{7+4\sqrt{5}}{\sqrt{5}}\frac{\sqrt{5}}{\sqrt{5}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{7\sqrt{5}+20}{5}\end{aligned} $$ | |
① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{5}} $$. |
② | Multiply in a numerator. $$ \color{blue}{ \left( 7 + 4 \sqrt{5}\right) } \cdot \sqrt{5} = \color{blue}{7} \cdot \sqrt{5}+\color{blue}{ 4 \sqrt{5}} \cdot \sqrt{5} = \\ = 7 \sqrt{5} + 20 $$ Simplify denominator. $$ \color{blue}{ \sqrt{5} } \cdot \sqrt{5} = 5 $$ |