CBSE Class 12 Mathematics 2026 Main Paper 65/3/3 · Q232 Marksmonotonicity
CBSE Class 12 Mathematics 2026 Main Paper 65/3/3 · Question 23 (Applications Of Derivatives)
Find where f(x)=x ln x increases on (0,∞).
✅ Step-by-Step Solution
Final Answer: (1/e,∞), with 1/e also valid as an endpoint.
- Differentiate to get f′=1+ln x.
- This is zero at x=1/e and positive for x>1/e.
- The function increases from 1/e onward.
📋 CBSE Stepwise Marking Scheme
- [0.5 marks] Differentiate to get f′=1+ln x.
- [1 mark] This is zero at x=1/e and positive for x>1/e.
- [0.5 marks] The function increases from 1/e onward.
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