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NCERT Class 12 · Ch 5 Exercise 5.2 · Q10

NCERT Class 12 Maths · Chapter 5 Continuity And Differentiability · Exercise 5.2 Question 10

Prove f(x)=⌊x⌋, 0<x<3, is not differentiable at x=1,2.
Floor function: jumps prevent derivatives
Floor function: jumps prevent derivatives

💡 Concept Hints

  1. Identify the domain and the inner and outer functions, or the relevant one-sided limits.
  2. Apply the appropriate differentiation or limit rule, keep all chain factors, and check exceptional points.

✅ Step-by-Step Solution

Final Answer: Neither derivative exists.
  1. At either integer n=1 or 2, f(n)=n; the left limit is n−1 while the right limit is n.
  2. The function is discontinuous at both points. Differentiability implies continuity, so it is not differentiable there.

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Prove f(x)=|x−1| is not differentiable at x=1.

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