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📐 Mathematics  ·  Continuity and Differentiability  ·  JEE

A function with LHL not equal to RHL at a point has what kind of discontinuity?

Answer: Jump discontinuity.

  • A Removable
  • B Jump discontinuity
  • C No discontinuity
  • D Infinite discontinuity

Correct answer: B. Jump discontinuity

Explanation: When the left-hand limit and right-hand limit exist but are unequal, the function has a jump (first kind) discontinuity.

f(x) = |x|: Continuous but NOT Differentiable at 0x=0 (sharp "kink")LHD = -1RHD = +1LHD ≠ RHD at the kink → not differentiable, even though the curve has no gap (continuous)

f(x)=|x| is perfectly continuous at x=0 (no break, no jump), but the curve has a sharp corner there: approaching from the left gives slope -1 and from the right gives slope +1 - since these one-sided derivatives disagree, the function is not differentiable at that point.

Concept context

When a function has no breaks (continuity) and when it has a well-defined slope (differentiability), plus rules for differentiating implicit, inverse trig, exponential, log, and parametric functions.

Read the full Continuity and Differentiability notes →