Math Problem Statement

For the limit below, find values of δ that correspond to the ε values. lim_(x->0) (e^x - 1)/x = 1 𝜀 𝛿 0.5

Incorrect: Your answer is incorrect. (Round your answer to three decimal places.)

Solution

We are given the limit:

limx0ex1x=1\lim_{{x \to 0}} \frac{e^x - 1}{x} = 1

The goal is to find values of δ\delta that correspond to a given ϵ\epsilon.

Definition of Limit:

For the limit limx0f(x)=L\lim_{{x \to 0}} f(x) = L, we say that the limit equals LL if, for every ϵ>0\epsilon > 0, there exists a δ>0\delta > 0 such that whenever 0<x0<δ0 < |x - 0| < \delta, the following holds:

f(x)L<ϵ|f(x) - L| < \epsilon

In this case, f(x)=ex1xf(x) = \frac{e^x - 1}{x} and L=1L = 1.

We need to satisfy:

ex1x1<ϵ\left| \frac{e^x - 1}{x} - 1 \right| < \epsilon

Simplifying the Expression:

ex1x1=ex1xx\left| \frac{e^x - 1}{x} - 1 \right| = \left| \frac{e^x - 1 - x}{x} \right| So we need:

ex1xx<ϵ\left| \frac{e^x - 1 - x}{x} \right| < \epsilon

Now, we must find δ\delta in terms of ϵ\epsilon.

Step-by-Step Solution:

  1. We need to solve for xx such that ex1xx<ϵ\left| \frac{e^x - 1 - x}{x} \right| < \epsilon.

  2. Approximate exe^x using the series expansion for small xx:

ex=1+x+x22+O(x3)e^x = 1 + x + \frac{x^2}{2} + O(x^3)

Thus, ex1xx22e^x - 1 - x \approx \frac{x^2}{2}, and we have:

x22x=x2\left| \frac{\frac{x^2}{2}}{x} \right| = \left| \frac{x}{2} \right|

  1. We now need x2<ϵ\left| \frac{x}{2} \right| < \epsilon, which gives:

x<2ϵ|x| < 2\epsilon

  1. Therefore, we can choose δ=2ϵ\delta = 2\epsilon.

For ϵ=0.5\epsilon = 0.5:

δ=2×0.5=1.0\delta = 2 \times 0.5 = 1.0

Thus, the corresponding δ\delta for ϵ=0.5\epsilon = 0.5 is δ=1.0\delta = 1.0.


Would you like a more detailed explanation or have any other questions?

Here are 5 related questions to explore:

  1. How do you find limits using the epsilon-delta definition?
  2. What is the Taylor series expansion of exe^x?
  3. How do you solve for δ\delta in terms of ϵ\epsilon in general?
  4. What are common limits involving exponential functions?
  5. How does the approximation ex1+xe^x \approx 1 + x for small xx help in solving limits?

Tip: When using the epsilon-delta definition, approximating complex functions with Taylor series can greatly simplify the problem.

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Math Problem Analysis

Mathematical Concepts

Limits
Epsilon-Delta Definition
Exponential Functions
Taylor Series Expansion

Formulas

lim_(x -> 0) (e^x - 1)/x = 1
|f(x) - L| < ε
e^x ≈ 1 + x + x^2/2 + O(x^3)

Theorems

Epsilon-Delta Definition of a Limit
Taylor Series Expansion

Suitable Grade Level

Grades 11-12, Early College