CalcRef

Applications of Derivatives · Applied Problems

Linearization

L(x)=f(a)+f′(a)(x−a)L(x) = f(a) + f'(a)(x - a)

The linearization of f at a is the tangent line, used as a linear approximation of f near a. This is the same as the first-degree Taylor polynomial.

Worked examples

Approximate √4.1 using linearization of f(x) = √x at a = 4.
  1. f(4) = 2, f'(x) = 1/(2√x), f'(4) = 1/4
  2. L(x) = 2 + (1/4)(x - 4)
  3. L(4.1) = 2 + (1/4)(0.1) = 2.025

Answer: √4.1 ≈ 2.025 (actual: 2.02485...)

Related formulas

Differentials

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