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MathsJEE Main 28 Jan 2026, Shift 2·Q5·MCQ·Tough

Limits, Continuity & Differentiability · Continuity of a limit-defined function

Let f(x)=lim⁡n→∞(cos⁡πx−x2nsin⁡(x−1)1+x2n(x−1)), x∈R.f(x) = \lim_{n\to\infty}\left(\dfrac{\cos\pi x - x^{2n}\sin(x-1)}{1 + x^{2n}(x-1)}\right),\ x \in \mathbb{R}. Consider the following two statements :

(I) f(x)f(x) is discontinuous at x=1x = 1.

(II) f(x)f(x) is continuous at x=−1x = -1.

Then,

  1. (1)Neither (I) nor (II) is True
  2. (2)Both (I) and (II) are True
  3. (3)Only (II) is True
  4. (4)Only (I) is True
We corrected a printing error in the original paper

Source printed “discontinous” and “continous”; source printed the limit as θ→0\theta\to0 with x(2/θ)x^{(2/\theta)} in place of x2nx^{2n} (undefined for x<0x<0, and the one-sided limits in θ\theta differ for 0<∣x∣<10<\lvert x\rvert<1); corrected to the intended n→∞n\to\infty with x2nx^{2n}, the reading the key uses.

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See the full 28 Jan 2026, Shift 2 paper