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CUET · MATHS · PYQ PAPER 2023

If \(f(x)=x+\frac{1}{x}\). Which of the following is not a correct option?

  1. A local minimum value \(=2\)
  2. B local maximum value \(=-2\), local minimum value \(=0\)
  3. C extremum occurs at \(1,-1\)
  4. D local maximum value \(=-2\)
Verified Solution

Answer & Solution

Correct Answer

(B) local maximum value \(=-2\), local minimum value \(=0\)

Step-by-step Solution

Detailed explanation

\(f(x)=x+x^{-1}\) \(f'(x)=1-x^{-2}\) \(1-x^{-2}=0 \implies x^2=1 \implies x=\pm 1\) \(f''(x)=2x^{-3}\) \(f''(1)=2 > 0 \implies \text{local min at } x=1\) \(f(1)=1+\frac{1}{1}=2\) \(f''(-1)=-2 \(f(-1)=-1+\frac{1}{-1}=-2\) Local minimum value \(=2\) Local maximum value…
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