Question
Answer
$$\dfrac{12}{7\sqrt{3}-2}=\dfrac{84\sqrt{3}+24}{143}$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{12}{7\sqrt{3}-2}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{12}{7\sqrt{3}-2}\frac{7\sqrt{3}+2}{7\sqrt{3}+2} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}\frac{84\sqrt{3}+24}{147+14\sqrt{3}-14\sqrt{3}-4} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle3}{\textcircled {3}} } }}}\frac{84\sqrt{3}+24}{143}\end{aligned} $$ | |
| ① | Multiply the numerator and denominator by the conjugate of the denominator . $$\color{blue}{ 7 \sqrt{3} + 2} $$. |
| ② | Multiply in a numerator. $$ \color{blue}{ 12 } \cdot \left( 7 \sqrt{3} + 2\right) = \color{blue}{12} \cdot 7 \sqrt{3}+\color{blue}{12} \cdot2 = \\ = 84 \sqrt{3} + 24 $$ Simplify denominator. $$ \color{blue}{ \left( 7 \sqrt{3}-2\right) } \cdot \left( 7 \sqrt{3} + 2\right) = \color{blue}{ 7 \sqrt{3}} \cdot 7 \sqrt{3}+\color{blue}{ 7 \sqrt{3}} \cdot2\color{blue}{-2} \cdot 7 \sqrt{3}\color{blue}{-2} \cdot2 = \\ = 147 + 14 \sqrt{3}- 14 \sqrt{3}-4 $$ |
| ③ | Simplify numerator and denominator |
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