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CUET · MATHS · PYQ PAPER 2023

The function \(f(x)=x+\cot ^{-1} x\) is increasing in the interval:

  1. A \((-\infty, \infty)\)
  2. B \((-1, \infty)\)
  3. C \((0, \infty)\)
  4. D \((1, \infty)\)
Verified Solution

Answer & Solution

Correct Answer

(A) \((-\infty, \infty)\)

Step-by-step Solution

Detailed explanation

\(f'(x) = 1 - \frac{1}{1+x^2}\) \(f'(x) = \frac{1+x^2-1}{1+x^2} = \frac{x^2}{1+x^2}\) For increasing function, \(f'(x) \ge 0\). \(\frac{x^2}{1+x^2} \ge 0\) Since \(x^2 \ge 0\) and \(1+x^2 > 0\) for all real \(x\), \(f'(x) \ge 0\) for all \(x \in \mathbb{R}\). Interval:…