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Which of the following inequalities holds true?

(A) 5+3>6+2\sqrt{5} + \sqrt{3} > \sqrt{6} + \sqrt{2}.

(B) If a>ba > b and c<0c < 0, then ac<bc\frac{a}{c} < \frac{b}{c}.

(C) 1x2>1x>1\frac{1}{x^2} > \frac{1}{x} > 1, if 0<x<10 < x < 1.

(D) If aa and bb are positive integers and a−b6.25=42.5\frac{a - b}{6.25} = \frac{4}{2.5}, then b>ab > a.

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 2

Statement (A): 5+3>6+2\sqrt{5} + \sqrt{3} > \sqrt{6} + \sqrt{2}

Both sides are positive, so squaring preserves the inequality direction.

Left side squared:

(5+3)2(\sqrt{5} + \sqrt{3})^2

=5+215+3= 5 + 2\sqrt{15} + 3

=8+215= 8 + 2\sqrt{15}

Right side squared:

(6+2)2(\sqrt{6} + \sqrt{2})^2

=6+212+2= 6 + 2\sqrt{12} + 2

=8+212= 8 + 2\sqrt{12}

Comparing 8+2158 + 2\sqrt{15} vs 8+2128 + 2\sqrt{12} reduces to comparing 15\sqrt{15} vs 12\sqrt{12}.

Since 15>1215 > 12, we have 15>12\sqrt{15} > \sqrt{12}.

Statement (A) is TRUE.


Statement (B): If a>ba > b and c<0c < 0, then ac<bc\frac{a}{c} < \frac{b}{c}

When dividing an inequality by a negative number, the inequality sign flips.

Starting with: a>ba > b

Dividing both sides by cc (where c<0c < 0):

ac<bc\frac{a}{c} < \frac{b}{c}

Example: If 5>35 > 3 and c=−2c = -2:

5−2=−2.5\frac{5}{-2} = -2.5

3−2=−1.5\frac{3}{-2} = -1.5

−2.5<−1.5-2.5 < -1.5

Statement (B) is TRUE.


Statement (C): 1x2>1x>1\frac{1}{x^2} > \frac{1}{x} > 1, if 0<x<10 < x < 1

Testing with x=0.5x = 0.5:

1x=10.5=2\frac{1}{x} = \frac{1}{0.5} = 2

1x2=10.25=4\frac{1}{x^2} = \frac{1}{0.25} = 4

This gives 4>2>14 > 2 > 1.

For 0<x<10 < x < 1:

Since x<1x < 1, we have 1x>1\frac{1}{x} > 1.

Since 0<x<10 < x < 1, multiplying by xx gives x2<xx^2 < x.

Taking reciprocals of positive numbers reverses the inequality: 1x2>1x\frac{1}{x^2} > \frac{1}{x}.

Statement (C) is TRUE.


Statement (D): If a−b6.25=42.5\frac{a - b}{6.25} = \frac{4}{2.5}, then b>ab > a

Simplifying the right side:

42.5=452\frac{4}{2.5} = \frac{4}{\frac{5}{2}}

=4×25= 4 \times \frac{2}{5}

=85= \frac{8}{5}

=1.6= 1.6

Solving for the relationship between aa and bb:

a−b6.25=1.6\frac{a - b}{6.25} = 1.6

a−b=1.6×6.25a - b = 1.6 \times 6.25

a−b=10a - b = 10

a=b+10a = b + 10

This means a>ba > b, NOT b>ab > a.

Statement (D) is FALSE.


Statements (A), (B), and (C) are TRUE.

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