ExamBro
ExamBro
CUET · MATHS · PYQ PAPER 2023

Which of the following function is increasing for all values of x in the domain \((0, \infty)\)?

  1. A 1 - x²
  2. B \(\frac{1}{x}\)
  3. C 8 - x²
  4. D x |x|
Verified Solution

Answer & Solution

Correct Answer

(D) x |x|

Step-by-step Solution

Detailed explanation

Let \(f(x) = x|x|\). For \(x \in (0, \infty)\), \(|x| = x\). Therefore, \(f(x) = x \cdot x = x^2\). \(f'(x) = \frac{d}{dx}(x^2) = 2x\). For \(x \in (0, \infty)\), \(2x > 0\). Thus, \(f(x)\) is increasing for all \(x \in (0, \infty)\).