Question : What is the value of the positive square root of $(69+28\sqrt{5})$?
Option 1: $(7+2\sqrt{5})$
Option 2: $(7-2\sqrt{5})$
Option 3: $(2+7\sqrt{5})$
Option 4: $(2-7\sqrt{5})$
Correct Answer: $(7+2\sqrt{5})$
Solution : Given: $x = 69+28\sqrt{5}$ $⇒ x = 49+20+2×7×2\sqrt{5}$ $⇒ x = 7^2+(2\sqrt{5})^2+2×7×2\sqrt{5}$ $⇒ x = (7+2\sqrt{5})^2$ So, the positive square root of $x$ is $(7+2\sqrt{5})$. Hence, the correct answer is $(7+2\sqrt{5})$.
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Question : $\frac{1}{3-\sqrt{8}}-\frac{1}{\sqrt{8}-\sqrt{7}}+\frac{1}{\sqrt{7}-\sqrt{6}}-\frac{1}{\sqrt{6}-\sqrt{5}}+\frac{1}{\sqrt{5}-2}=?$
Option 1: 5
Option 2: 4
Option 3: 3
Option 4: 2
Question : If $a-\frac{1}{a}=4$, then the value of $a+\frac{1}{a}$ is:
Option 1: $5 \sqrt{5}$
Option 2: $4 \sqrt{5}$
Option 3: $2 \sqrt{5}$
Option 4: $3 \sqrt{5}$
Question : If $\left (\sqrt{5} \right)^{7}\div \left (\sqrt{5} \right)^{5}=5^{p},$ then the value of $p$ is:
Option 1: $5$
Option 2: $2$
Option 3: $\frac{3}{2}$
Option 4: $1$
Question : If $x^2+\frac{1}{x^2}=\frac{7}{4}$ for $x>0$, what is the value of $(x^3+\frac{1}{x^3})$?
Option 1: $\frac{3\sqrt{3}}{5}$
Option 2: $\frac{3\sqrt{15}}{5}$
Option 3: $\frac{3\sqrt{15}}{8}$
Option 4: $\frac{3\sqrt{5}}{8}$
Question : Which is the largest among the numbers $\sqrt{5},\ 3\sqrt{7}$ and $4\sqrt{13}$.
Option 1: $\sqrt{5}$
Option 2: $3\sqrt{7}$
Option 3: $4\sqrt{13}$
Option 4: All are equal
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