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

The question in the uploaded image involves using a local linear approximation (or tangent line approximation) to estimate f(4.8)f(4.8). Here's the breakdown and solution:


Problem Details:

  • Given:
    • f(5)=3f(5) = 3
    • f(5)=4f'(5) = 4
  • Estimate f(4.8)f(4.8) using the local linear approximation.

Solution:

The local linear approximation formula is: f(x)f(a)+f(a)(xa)f(x) \approx f(a) + f'(a)(x - a) where aa is the point of tangency, and xx is the value we want to approximate.

Here:

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

Substitute these values into the formula: f(4.8)f(5)+f(5)(4.85)f(4.8) \approx f(5) + f'(5)(4.8 - 5) f(4.8)3+4(0.2)f(4.8) \approx 3 + 4(-0.2) f(4.8)30.8f(4.8) \approx 3 - 0.8 f(4.8)2.2f(4.8) \approx 2.2

Thus, the estimate for f(4.8)f(4.8) is 2.22.2, which matches choice A.


Do you want further clarification or more details?

Here are 5 follow-up questions to expand your understanding:

  1. What is the geometric interpretation of a tangent line approximation?
  2. How would the approximation change if f(5)f'(5) were negative?
  3. What is the error involved in using linear approximation versus the actual value?
  4. How could you use a quadratic approximation to improve accuracy?
  5. Can you derive the formula for local linear approximation from the definition of a derivative?

Tip:

For small changes near aa, the tangent line is a very close estimate of the function. However, as xx moves further away, the approximation may deviate significantly!

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Math Problem Analysis

Mathematical Concepts

Local Linear Approximation
Differentiation
Tangent Line Approximation

Formulas

f(x) ≈ f(a) + f'(a)(x - a)

Theorems

Linear Approximation Theorem

Suitable Grade Level

Grades 11-12 (High School Calculus)