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CUET · MATHS · PYQ PAPER 2025

For the function \(f(x)=x^{1 / x}, x>0\), which of the following are correct?
(A) \(x=0\) is the only point where extremum may occur.
(B) The given function is maximum at \(x=e\).
(C) The function has no extreme value for \(x>0\).
(D) The maximum value of the function \(f(x)\) is \(e^{1 / e}\)
Choose the correct answer from the options given below :

  1. A (A), (B) and (D) only
  2. B (A) and (C) only
  3. C (C) and (D) only
  4. D (B) and (D) only
Verified Solution

Answer & Solution

Correct Answer

(D) (B) and (D) only

Step-by-step Solution

Detailed explanation

\(\ln f(x) = \frac{\ln x}{x}\) \(\frac{f'(x)}{f(x)} = \frac{\frac{1}{x} \cdot x - \ln x \cdot 1}{x^2} = \frac{1 - \ln x}{x^2}\) \(f'(x) = x^{1/x} \frac{1 - \ln x}{x^2}\) \(f'(x) = 0 \Rightarrow 1 - \ln x = 0 \Rightarrow \ln x = 1 \Rightarrow x = e\) For…
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