Math Problem Statement

Use the given graph of f to find a number δ such that if 0 < |x - 3| < δ then |f(x) - 2| < 0.5.

Solution

The question is asking to find a value of δ\delta such that for all xx, if 0<x3<δ0 < |x - 3| < \delta, then f(x)2<0.5|f(x) - 2| < 0.5. This is related to the definition of continuity, specifically in terms of the epsilon-delta definition of limits.

Analyzing the graph:

  • The horizontal line y=2y = 2 is relevant because we are interested in how the function f(x)f(x) deviates from 2.
  • The condition f(x)2<0.5|f(x) - 2| < 0.5 means we are looking for where the function lies between 1.5 and 2.5 (as 20.5=1.52 - 0.5 = 1.5 and 2+0.5=2.52 + 0.5 = 2.5).
  • From the graph, this means we are interested in the interval where the graph of f(x)f(x) lies between these two values of yy.

Now, we need to determine for which values of xx, f(x)f(x) is between 1.5 and 2.5:

  • At f(2.6)f(2.6), the graph is approximately at 1.5.
  • At f(3.8)f(3.8), the graph reaches 2.5.

Therefore, f(x)2<0.5|f(x) - 2| < 0.5 holds when xx is between approximately 2.6 and 3.8. Since the problem asks for x3<δ|x - 3| < \delta, we can infer the distance from x=3x = 3 to these boundary points.

Solution:

  • The distance from 3 to 2.6 is 32.6=0.43 - 2.6 = 0.4.
  • The distance from 3 to 3.8 is 3.83=0.83.8 - 3 = 0.8.

Therefore, δ\delta can be the smaller of these two values, which is δ=0.4\delta = 0.4.

Thus, δ=0.4\delta = 0.4.

Would you like a deeper explanation of how this ties into the epsilon-delta definition of limits?

Related questions:

  1. What is the epsilon-delta definition of limits?
  2. How do you determine delta given epsilon in a limit problem?
  3. Why is δ=0.4\delta = 0.4 chosen instead of 0.8 in this case?
  4. How do continuity and limits relate to each other in calculus?
  5. How can graphing help to solve limit problems visually?

Tip: In epsilon-delta limit problems, always focus on the range for f(x)f(x) (based on epsilon) and find the corresponding interval for xx around the given point.

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Math Problem Analysis

Mathematical Concepts

Limits
Continuity
Epsilon-Delta Definition

Formulas

|f(x) - L| < ε for |x - c| < δ

Theorems

Epsilon-Delta Definition of Limits

Suitable Grade Level

Grades 11-12 (Calculus)