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📐 Mathematics  ·  Continuity and Differentiability  ·  JEE

The derivative measures the ___ of a function at a point:

Answer: instantaneous rate of change.

  • A instantaneous rate of change
  • B the total enclosed area
  • C the average value only
  • D the solid volume value

Correct answer: A. instantaneous rate of change

Explanation: The derivative is the instantaneous rate of change (the slope of the tangent).

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 →