Question
Answer
$$\dfrac{(9-\sqrt{11})\cdot(9+\sqrt{11})}{1}=70$$
Explanation
Tap the blue circles to see an explanation.
| $$ \begin{aligned}\frac{(9-\sqrt{11})\cdot(9+\sqrt{11})}{1}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{81+9\sqrt{11}-9\sqrt{11}-11}{1} \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}70\end{aligned} $$ | |
| ① | $$ \color{blue}{ \left( 9- \sqrt{11}\right) } \cdot \left( 9 + \sqrt{11}\right) = \color{blue}{9} \cdot9+\color{blue}{9} \cdot \sqrt{11}\color{blue}{- \sqrt{11}} \cdot9\color{blue}{- \sqrt{11}} \cdot \sqrt{11} = \\ = 81 + 9 \sqrt{11}- 9 \sqrt{11}-11 $$ |
| ② | Remove 1 from denominator. |
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