Math Problem Statement

Evaluate the limit using L'Hôpital's Rule: \( \lim_{{x \to 0}} \frac{4e^x - 4x - 4}{13x^2} \).

Solution

We are asked to evaluate the limit:

limx04ex4x413x2\lim_{{x \to 0}} \frac{4e^x - 4x - 4}{13x^2}

Step 1: Check for Indeterminate Form

Substitute x=0x = 0 directly into the expression:

4e04(0)413(0)2=440=00\frac{4e^0 - 4(0) - 4}{13(0)^2} = \frac{4 - 4}{0} = \frac{0}{0}

Since the limit results in the indeterminate form 00\frac{0}{0}, we can apply L'Hôpital's Rule, which allows us to differentiate the numerator and denominator until the limit is no longer indeterminate.

Step 2: Apply L'Hôpital's Rule

Differentiate the numerator and denominator separately.

  • Numerator: The derivative of 4ex4x44e^x - 4x - 4 is: ddx(4ex4x4)=4ex4\frac{d}{dx}(4e^x - 4x - 4) = 4e^x - 4

  • Denominator: The derivative of 13x213x^2 is: ddx(13x2)=26x\frac{d}{dx}(13x^2) = 26x

Thus, the limit becomes:

limx04ex426x\lim_{{x \to 0}} \frac{4e^x - 4}{26x}

Step 3: Check the New Indeterminate Form

Substitute x=0x = 0 again:

4e0426(0)=440=00\frac{4e^0 - 4}{26(0)} = \frac{4 - 4}{0} = \frac{0}{0}

We still have the indeterminate form 00\frac{0}{0}, so we apply L'Hôpital's Rule again.

Step 4: Apply L'Hôpital's Rule Again

Differentiate the numerator and denominator again.

  • Numerator: The derivative of 4ex44e^x - 4 is: ddx(4ex4)=4ex\frac{d}{dx}(4e^x - 4) = 4e^x

  • Denominator: The derivative of 26x26x is: ddx(26x)=26\frac{d}{dx}(26x) = 26

Thus, the limit becomes:

limx04ex26\lim_{{x \to 0}} \frac{4e^x}{26}

Step 5: Evaluate the Final Limit

Substitute x=0x = 0:

4e026=4×126=426=213\frac{4e^0}{26} = \frac{4 \times 1}{26} = \frac{4}{26} = \frac{2}{13}

Conclusion:

The value of the limit is:

213\boxed{\frac{2}{13}}


Would you like further details or have any other questions?

Here are five related questions to consider:

  1. How do you apply L'Hôpital's Rule to more complex limits?
  2. What are the conditions under which L'Hôpital's Rule can be used?
  3. How would this limit change if the exponent in exe^x was higher, say e2xe^{2x}?
  4. What other techniques can you use to solve limits if L'Hôpital’s Rule is not applicable?
  5. Can L'Hôpital’s Rule be used for limits approaching infinity?

Tip: Always check the indeterminate form before applying L'Hôpital's Rule, as it can only be applied to specific forms like 00\frac{0}{0} or \frac{\infty}{\infty}.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Calculus
Differentiation
L'Hôpital's Rule

Formulas

L'Hôpital's Rule: \( \lim_{{x \to c}} \frac{f(x)}{g(x)} = \lim_{{x \to c}} \frac{f'(x)}{g'(x)} \) when \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \)
Derivative of \( e^x \): \( \frac{d}{dx}(e^x) = e^x \)

Theorems

L'Hôpital's Rule

Suitable Grade Level

Grades 11-12, College Introductory Calculus