CBSE Class 12 Mathematics 2026 Main Paper 65/3/1 · Q222 Marksmonotonicity
CBSE Class 12 Mathematics 2026 Main Paper 65/3/1 · Question 22 (Applications Of Derivatives)
Find where f(x)=tan x−4x increases on (0,π/2).
✅ Step-by-Step Solution
Final Answer: Increasing on (π/3,π/2), also including π/3 as a left endpoint.
- Differentiate to get f′=sec²x−4.
- On (0,π/2) this vanishes at π/3 and is positive to its right.
- The function increases from π/3 up to π/2.
📋 CBSE Stepwise Marking Scheme
- [0.5 marks] Differentiate to get f′=sec²x−4.
- [1 mark] On (0,π/2) this vanishes at π/3 and is positive to its right.
- [0.5 marks] The function increases from π/3 up to π/2.
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