Math Problem Statement

Use the graph of f(x)=1/x

below to find a number δ

such that |f(x)−0.5|<0.1

whenever 0<|x−2|<δ

.

Use the graph of f(x)=1/x below to find a number δ such that |f(x)−0.5|<0.1 whenever 0<|x−2|<δ.

Solution

The graph provided is of the function f(x)=1xf(x) = \frac{1}{x}. We are tasked with finding a number δ\delta such that:

f(x)0.5<0.1|f(x) - 0.5| < 0.1

whenever 0<x2<δ0 < |x - 2| < \delta.

Step-by-step process:

  1. Express the condition: We need to satisfy the condition f(x)0.5<0.1|f(x) - 0.5| < 0.1, where f(x)=1xf(x) = \frac{1}{x}. Substituting this into the inequality, we get: 1x0.5<0.1\left| \frac{1}{x} - 0.5 \right| < 0.1

  2. Simplify the inequality: To simplify this, we first rewrite the absolute value expression: 1x0.5=1x12\left| \frac{1}{x} - 0.5 \right| = \left| \frac{1}{x} - \frac{1}{2} \right| This becomes: 2x2x<0.1\left| \frac{2 - x}{2x} \right| < 0.1

  3. Solve for xx: To solve this inequality, we first multiply both sides by 2x2x (assuming x>0x > 0, since the graph is valid for x>0x > 0): 2x<0.2x\left| 2 - x \right| < 0.2x

  4. Consider the two cases:

    • Case 1: 2x<0.2x2 - x < 0.2x and
    • Case 2: (2x)<0.2x-(2 - x) < 0.2x

Let's solve these two cases. I will calculate the solution. sympy import symbols, Eq, solve

Define variables

x = symbols('x')

Case 1: 2 - x < 0.2x

eq1 = Eq(2 - x, 0.2 * x) sol_case1 = solve(eq1, x)

Case 2: -(2 - x) < 0.2x

eq2 = Eq(-(2 - x), 0.2 * x) sol_case2 = solve(eq2, x)

sol_case1, sol_case2The solutions to the two cases are:

  • For Case 1: x=1.67x = 1.67
  • For Case 2: x=2.5x = 2.5

Interpretation of the results:

The inequality f(x)0.5<0.1|f(x) - 0.5| < 0.1 holds when xx lies between these two values, i.e., for 1.67<x<2.51.67 < x < 2.5.

Therefore, the value of δ\delta should be the smallest distance from x=2x = 2 to the boundary points 1.67 and 2.5. The closest boundary is at x=2.5x = 2.5, and the distance from 2 to 2.5 is:

δ=2.52=0.5\delta = 2.5 - 2 = 0.5

Thus, δ=0.5\delta = 0.5.

Would you like further clarification or details on this solution?

Additional questions for you:

  1. How do you verify the value of δ\delta in real-world applications?
  2. How would this problem change if the function were different, say f(x)=x2f(x) = x^2?
  3. What is the significance of the condition f(x)0.5<0.1|f(x) - 0.5| < 0.1 in terms of the graph?
  4. Can you extend this method to find a similar δ\delta for any function f(x)f(x)?
  5. How does the concept of limits relate to the condition f(x)0.5<0.1|f(x) - 0.5| < 0.1?

Tip: When solving inequalities like this, it helps to break the absolute value into cases to simplify the expression!

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Math Problem Analysis

Mathematical Concepts

Graph Analysis
Inequalities
Limits

Formulas

f(x) = 1/x
|f(x) - 0.5| < 0.1

Theorems

Epsilon-Delta Definition of Limits

Suitable Grade Level

Undergraduate Mathematics or Advanced High School (Grades 11-12)