Math Problem Statement

A differentiable function f has the property that f(5) = 3 and f'(5) = 4. What is the estimate for f(4.8) using the local linear approximation for f at x = 5?

Solution

This problem involves estimating f(4.8)f(4.8) using the local linear approximation (or tangent line approximation) for the function f(x)f(x) at x=5x = 5.

The formula for the local linear approximation is: f(x)f(a)+f(a)(xa),f(x) \approx f(a) + f'(a)(x - a), where:

  • a=5a = 5,
  • f(a)=f(5)=3f(a) = f(5) = 3,
  • f(a)=f(5)=4f'(a) = f'(5) = 4,
  • x=4.8x = 4.8.

Step-by-step solution:

  1. Substitute values into the formula: f(4.8)f(5)+f(5)(4.85).f(4.8) \approx f(5) + f'(5)(4.8 - 5). Substituting f(5)=3f(5) = 3, f(5)=4f'(5) = 4, and 4.85=0.24.8 - 5 = -0.2, we get: f(4.8)3+4(0.2).f(4.8) \approx 3 + 4(-0.2).

  2. Simplify the expression: f(4.8)30.8=2.2.f(4.8) \approx 3 - 0.8 = 2.2.

Final Answer:

The estimate for f(4.8)f(4.8) is 2.2\mathbf{2.2} (Option A).


Would you like further explanation or details on linear approximations? Here are related questions to explore:

  1. How is the linear approximation derived from the tangent line equation?
  2. Why is f(x)f'(x) (the derivative) crucial for making these approximations?
  3. How does this method differ from other numerical estimation techniques?
  4. What is the accuracy of local linear approximations, and when do they fail?
  5. Can the linear approximation formula be used for larger deviations from aa?

Tip: The closer xx is to aa, the more accurate the linear approximation will be!

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Math Problem Analysis

Mathematical Concepts

Differentiation
Tangent Line Approximation
Linear Approximation

Formulas

f(x) ≈ f(a) + f'(a)(x - a)

Theorems

Linear Approximation Theorem
Derivative as Slope of Tangent Line

Suitable Grade Level

Grades 11-12