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GATE 2023 MN – Question 40

Engineering Mathematics · Calculus · 2 marks · Multiple choice

For $f(x)=|x|+|x-1|$ and real x, which statement is correct?

  1. Continuous and nondifferentiable at one point
  2. Continuous and nondifferentiable at two points
  3. Discontinuous
  4. Continuous and differentiable everywhere

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Correct answer: (B) Continuous and nondifferentiable at two points

Explanation

Both absolute-value terms are continuous. The piecewise function is 1−2x for x<0, 1 for 0≤x≤1, and 2x−1 for x>1. Slopes change from −2 to 0 at x=0 and from 0 to 2 at x=1. It is therefore continuous but nondifferentiable at two points, B.

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