Question
Answer
$$\dfrac{3}{4\sqrt{7}-2}=\dfrac{2\sqrt{7}+1}{18}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{3}{4\sqrt{7}-2}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{3}{4\sqrt{7}-2}\frac{4\sqrt{7}+2}{4\sqrt{7}+2} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{12\sqrt{7}+6}{112+8\sqrt{7}-8\sqrt{7}-4} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{12\sqrt{7}+6}{108} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle4}{\textcircled {4}} } }}}\frac{2\sqrt{7}+1}{18}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 4 \sqrt{7} + 2} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 3 } \cdot \left( 4 \sqrt{7} + 2\right) = \color{blue}{3} \cdot 4 \sqrt{7}+\color{blue}{3} \cdot2 = \\ = 12 \sqrt{7} + 6 $$ Simplify denominator. $$ \color{blue}{ \left( 4 \sqrt{7}-2\right) } \cdot \left( 4 \sqrt{7} + 2\right) = \color{blue}{ 4 \sqrt{7}} \cdot 4 \sqrt{7}+\color{blue}{ 4 \sqrt{7}} \cdot2\color{blue}{-2} \cdot 4 \sqrt{7}\color{blue}{-2} \cdot2 = \\ = 112 + 8 \sqrt{7}- 8 \sqrt{7}-4 $$ |
| ③ | Simplify numerator and denominator |
| ④ | Divide both numerator and denominator by 6. |
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