Question : If $a=\sqrt{6}–\sqrt{5}$, $b=\sqrt{5}–2$, and $c=2–\sqrt{3}$, then point out the correct alternative among the four alternatives given below.
Option 1: $b<a<c$
Option 2: $a<c<b$
Option 3: $b<c<a$
Option 4: $a<b<c$
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Correct Answer: $a<b<c$
Solution : Given: $a=\sqrt{6}–\sqrt{5}$, $b=\sqrt{5}–2$, $c=2–\sqrt{3}$ Rationalising the given values, $a=\sqrt{6}–\sqrt{5}×\frac{\sqrt{6}+\sqrt{5}}{\sqrt{6}+\sqrt{5}}$ ⇒ $a=\frac{1}{\sqrt{6}+\sqrt{5}}$ -----(1) $b=\sqrt{5}–2×\frac{\sqrt{5}+2}{\sqrt{5}+2}$ ⇒ $b=\frac{1}{\sqrt{5}+2}$ ⇒ $b=\frac{1}{\sqrt{5}+\sqrt{4}}$------(2) $c=2–\sqrt{3}×\frac{2+\sqrt{3}}{2+\sqrt{3}}$ ⇒ $c=\frac{1}{2+\sqrt{3}}$ ⇒ $c=\frac{1}{\sqrt{4}+\sqrt{3}}$------(3) By comparing $(a,b,c)$ we can find $a<b<c$. Hence, the correct answer is $a<b<c$.
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Question : Which of the following is true?
Option 1: $\sqrt 5 + \sqrt 3 > \sqrt 6 + \sqrt 2$
Option 2: $\sqrt 5 + \sqrt 3 < \sqrt 6 + \sqrt 2$
Option 3: $\sqrt 5 + \sqrt 3 = \sqrt 6 + \sqrt 2$
Option 4: $(\sqrt 5 + \sqrt 3 ) (\sqrt 6 + \sqrt 2 )= 1$
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 5x + 3y = 15 and 2xy = 6, then the value of 5x – 3y is:
Option 1: $3\sqrt{3}$
Option 2: $3\sqrt{5}$
Option 3: $3\sqrt{2}$
Option 4: $3\sqrt{4}$
Question : If $x=5–\sqrt{21}$, the value of $\frac{\sqrt{x}}{\sqrt{32–2x}–\sqrt{21}}$ is:
Option 1: $\frac{1}{\sqrt2}(\sqrt{3}–\sqrt{7})$
Option 2: $\frac{1}{\sqrt2}(\sqrt{7}–\sqrt{3})$
Option 3: $\frac{1}{\sqrt2}(\sqrt{7}+\sqrt{3})$
Option 4: $\frac{1}{\sqrt2}(7–\sqrt{3})$
Question : Directions: By interchanging the given two numbers (not digits) which of the following equations will not be correct? 4 and 6
Option 1: 2 + 6 × 5 – 4 = 16
Option 2: 4 + 5 – 6 = 7
Option 3: 6 ÷ 2 – 4 × 5 = –28
Option 4: 6 × 3 – 4 ÷ 1 = 3
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