Math Problem Statement

when demonstrating that lim(x->2) 2x+2=6 with e =0.2 which of the following values suffices

Solution

To demonstrate that limx2(2x+2)=6\lim_{x \to 2} (2x + 2) = 6 with ϵ=0.2\epsilon = 0.2, we need to find a value of δ\delta that satisfies the definition of a limit:

For all x, if 0<x2<δ, then (2x+2)6<0.2.\text{For all } x, \text{ if } 0 < |x - 2| < \delta, \text{ then } |(2x + 2) - 6| < 0.2.

Step-by-step:

  1. Start with the inequality: (2x+2)6<0.2.|(2x + 2) - 6| < 0.2.

  2. Simplify: 2x+26=2x4=2x2.|2x + 2 - 6| = |2x - 4| = 2|x - 2|.

    So we need: 2x2<0.2.2|x - 2| < 0.2.

  3. Solve for x2|x - 2|: x2<0.22=0.1.|x - 2| < \frac{0.2}{2} = 0.1.

Thus, a value of δ=0.1\delta = 0.1 suffices to ensure that (2x+2)6<0.2|(2x + 2) - 6| < 0.2.

Conclusion:

For ϵ=0.2\epsilon = 0.2, δ=0.1\delta = 0.1 is sufficient to demonstrate that limx2(2x+2)=6\lim_{x \to 2} (2x + 2) = 6.


Do you want further details or have any questions?

Here are 5 related questions:

  1. How would you find δ\delta for a different ϵ\epsilon value, such as ϵ=0.1\epsilon = 0.1?
  2. Can you explain how the formal definition of a limit works?
  3. What happens if you use a larger δ\delta value, like δ=0.2\delta = 0.2?
  4. How can this limit be visualized on a graph of the function f(x)=2x+2f(x) = 2x + 2?
  5. What are the key steps in finding δ\delta for any general limit problem?

Tip: Always simplify the inequality after substituting the limit into the function to find δ\delta.

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Math Problem Analysis

Mathematical Concepts

Limits
Epsilon-Delta Definition of a Limit

Formulas

|f(x) - L| < ε when 0 < |x - c| < δ

Theorems

Epsilon-Delta Definition of a Limit

Suitable Grade Level

Grades 11-12