Question
Answer
$$\dfrac{6\sqrt{3}-5\sqrt{5}}{7\sqrt{20}}=\dfrac{6\sqrt{15}-25}{70}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{6\sqrt{3}-5\sqrt{5}}{7\sqrt{20}}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{6\sqrt{3}-5\sqrt{5}}{7\sqrt{20}}\frac{\sqrt{20}}{\sqrt{20}} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{12\sqrt{15}-50}{140} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{6\sqrt{15}-25}{70}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ \sqrt{20}} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ \left( 6 \sqrt{3}- 5 \sqrt{5}\right) } \cdot \sqrt{20} = \color{blue}{ 6 \sqrt{3}} \cdot \sqrt{20}\color{blue}{- 5 \sqrt{5}} \cdot \sqrt{20} = \\ = 12 \sqrt{15}-50 $$ Simplify denominator. $$ \color{blue}{ 7 \sqrt{20} } \cdot \sqrt{20} = 140 $$ |
| ③ | Divide both numerator and denominator by 2. |
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