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GATE 2021 ST – Question 37

Calculus · Single Variable Calculus · 2 marks · Multiple choice

For f:[0,∞)→ℝ,which statement is true?

  1. Bounded continuous f is uniformly continuous.
  2. Uniformly continuous f has a limit as x→∞.
  3. Uniform continuity of f implies uniform continuity of f(x)sin x.
  4. If f is continuous and has a finite limit at infinity,then f is uniformly continuous.

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Correct answer: (D) If f is continuous and has a finite limit at infinity,then f is uniformly continuous.

Explanation

D follows by controlling the tail using the finite limit and the remaining compact interval using uniform continuity there. A fails for sin(x²). B fails for sin x. C fails for f(x)=x,which is uniformly continuous,but x sin x has fixed output changes across shrinking input gaps near 2πn. **D**.

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