Applications of Derivatives · Applied Problems

Differentials

dy=f(x)dxdy = f'(x)\, dx

The differential dy approximates the change in y for a small change dx. Used for error estimation and approximation.

Worked examples

Use differentials to approximate the change in y = x³ when x changes from 2 to 2.01.
  1. dy = f'(x) dx = 3x² dx
  2. dy = 3(4)(0.01) = 0.12

Answer: dy = 0.12 (actual Δy = 0.120601)

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