Question : If $x^2-\sqrt{9.76} x+1=0$ and $x>1$, then the value of $\left(x^3-\frac{1}{x^3}\right)$ is:
Option 1: 21.042
Option 2: 24.024
Option 3: 21.024
Option 4: 24.042
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Correct Answer: 21.024
Solution : Given, $x^2-\sqrt{9.76} x+1=0$ Dividing by $x$, we get, $⇒x-\sqrt{9.76} +\frac{1}{x}=0$ $⇒x +\frac{1}{x}=\sqrt{9.76}$ Squaring both sides, we get, $⇒x^2+\frac{1}{x^2}+2×x×\frac{1}{x}=9.76$ Subtracting 4 from both sides, we get, $⇒x^2+\frac{1}{x^2}-2=9.76-4$ $⇒(x -\frac{1}{x})^2=5.76$ $⇒(x -\frac{1}{x})=\sqrt{5.76}$ Cubing both sides, we get, $⇒ x^3-\frac{1}{x^3}-3×x×\frac{1}{x}(x-\frac{1}{x})=5.76×\sqrt{5.76}$ $⇒ x^3-\frac{1}{x^3}-3×\sqrt{5.76}=5.76×\sqrt{5.76}$ $⇒ x^3-\frac{1}{x^3}=5.76×\sqrt{5.76}+3×\sqrt{5.76}$ $⇒ x^3-\frac{1}{x^3}=8.76×\sqrt{\frac{576}{100}}=8.76×\frac{24}{10}=21.024$ Hence, the correct answer is 21.024.
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Question : If $x=(\sqrt{6}-1)^{\frac{1}{3}}$, then the value of $\left(x-\frac{1}{x}\right)^3+3\left(x-\frac{1}{x}\right)$ is:
Option 1: $\frac{2 \sqrt{6}-6}{5}$
Option 2: $\frac{4 \sqrt{6}-6}{5}$
Option 3: $\frac{4 \sqrt{6}-6}{3}$
Option 4: $\frac{4 \sqrt{3}-6}{5}$
Question : If $\left(x+\frac{1}{x}\right)=5 \sqrt{2}$, and $x>1$, what is the value of $\left(x^6-\frac{1}{x^6}\right) ?$
Option 1: $22970 \sqrt{23}$
Option 2: $23030 \sqrt{23}$
Option 3: $23060 \sqrt{23}$
Option 4: $22960 \sqrt{23}$
Question : If $x=\frac{1}{x-5}(x>0)$, then the value of $x+\frac{1}{x}$ is:
Option 1: $\sqrt{41}$
Option 2: $\sqrt{29}$
Option 3: $\sqrt{23}$
Option 4: $\sqrt{43}$
Question : If $a+b :\sqrt{ab} = 4:1 $ where $ a > b > 0$, then $ a:b$ is:
Option 1: $\left (2+\sqrt{3} \right):\left (2-\sqrt{3} \right)$
Option 2: $\left (2-\sqrt{3} \right):\left (2+\sqrt{3} \right)$
Option 3: $\left (3+\sqrt{2} \right):\left (3-\sqrt{2} \right)$
Option 4: $\left (3-\sqrt{2} \right):\left (3+\sqrt{2} \right)$
Question : If $x^3=270+y^3$ and $x=(6+y)$, then what is the value of $(x+y)? $(given that $x>0$ and $y>0$)
Option 1: $2 \sqrt{3}$
Option 2: $\sqrt{3}$
Option 3: $4 \sqrt{3}$
Option 4: $4 \sqrt{2}$
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