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Bunuel
If a and b are both positive, is a < 5 < b?

(1) a < b and ab = 25
(2) a^2 < 25 < b^2

Given, a>0 and b>0

Question stem:- Is a < 5 < b?

St1:- a < b and ab = 25

We have , a<b
Or, a*b < b*b
Or, \(ab < b^2\)
Or, 25 < b^2[/m]------------(1)

Similarly, a < b
Or, a*a < b*a
Or, \(a^2 < ab\)
Or, \(a^2 < 25\)--------(2)

Note:- We were able to multiply variables on both sides91 of the inequality since a and b are positive.
On the same reasoning, we will take the square root of equation(1) and (2).

From (1) and (2), we have,
\(a^2 < 25 < b^2\)-----------(3)
Or, \(\sqrt{a^2} < \sqrt{25} < \sqrt{b^2}\)
Or, a < 5 < b

Sufficient.

St2:- Given, \(a^2 < 25 < b^2\)
Applying square root operation on both sides.
\(\sqrt{a^2} < \sqrt{25} < \sqrt{b^2}\)
Or, a < 5 < b

Sufficient.

Ans. (D)

P.S:- We could solve it without number plug-in.
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