Math Problem Statement

Evaluate \(\lim_{x \to 0} \left( 1 - e^{\tan^2(\sqrt{x})} \right)^{\frac{1}{\sqrt[3]{x^2}}}\).

Solution

The mathematical expression in the image reads:

limx0(1etan2(x))1x23.\lim_{x \to 0} \left( 1 - e^{\tan^2\left(\sqrt{x}\right)} \right)^{\frac{1}{\sqrt[3]{x^2}}}.

Let’s solve it step by step:


Step 1: Analyze the Limit

We are taking a limit as x0x \to 0. Inside the expression:

  1. tan2(x)0\tan^2(\sqrt{x}) \to 0 as x0x \to 0, since tan(0)=0\tan(0) = 0.
  2. This implies etan2(x)e0=1e^{\tan^2(\sqrt{x})} \to e^0 = 1.
  3. Therefore, 1etan2(x)01 - e^{\tan^2(\sqrt{x})} \to 0.

However, the exponent 1x23\frac{1}{\sqrt[3]{x^2}} diverges to \infty as x0+x \to 0^+. This results in an indeterminate form of the type 00^\infty. To resolve this, we apply logarithmic techniques.


Step 2: Apply the Natural Logarithm

Let L=limx0(1etan2(x))1x23L = \lim_{x \to 0} \left( 1 - e^{\tan^2(\sqrt{x})} \right)^{\frac{1}{\sqrt[3]{x^2}}}.

Take the natural logarithm of both sides: lnL=limx0ln(1etan2(x))x23.\ln L = \lim_{x \to 0} \frac{\ln\left( 1 - e^{\tan^2(\sqrt{x})} \right)}{\sqrt[3]{x^2}}.

Now, the problem reduces to evaluating the limit of the logarithmic term: ln(1etan2(x)).\ln\left(1 - e^{\tan^2(\sqrt{x})}\right).


Step 3: Expand Using Approximation

For small xx, we use the series expansions:

  1. tan2(x)x2=x\tan^2(\sqrt{x}) \approx \sqrt{x}^2 = x, since tan(z)z\tan(z) \approx z for small zz.
  2. etan2(x)ex1+xe^{\tan^2(\sqrt{x})} \approx e^x \approx 1 + x for small xx.
  3. Therefore, 1etan2(x)1(1+x)=x1 - e^{\tan^2(\sqrt{x})} \approx 1 - (1 + x) = -x.

Substitute into the logarithm: ln(1etan2(x))ln(x).\ln\left(1 - e^{\tan^2(\sqrt{x})}\right) \approx \ln(-x).


Step 4: Substitute and Simplify

Rewrite the limit: lnL=limx0ln(x)x23.\ln L = \lim_{x \to 0} \frac{\ln(-x)}{\sqrt[3]{x^2}}.

(At this step, we would need to ensure if x0+x \to 0^+ or x0x \to 0^-, as negative logarithms arise. Would you like to clarify?)


Let me know how much detail you'd like to proceed further or if clarification is needed!


5 Questions for Deeper Understanding:

  1. What is the significance of resolving 00^\infty indeterminate forms in limits?
  2. How does the logarithmic method simplify exponentiation limits?
  3. Why does tan2(x)\tan^2(\sqrt{x}) simplify to xx for small values of xx?
  4. What happens if xx approaches 00 from the negative side instead?
  5. Can we use L’Hôpital’s Rule in this problem? If yes, how?

Tip: When dealing with exponential limits, always consider logarithmic simplifications to reduce complexity.

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Math Problem Analysis

Mathematical Concepts

Limits
Exponential and Logarithmic Functions
Taylor Series Expansion
Indeterminate Forms

Formulas

Natural logarithm property: \(\ln(a^b) = b \cdot \ln(a)\)
First-order Taylor expansion: \(e^x \approx 1 + x\) for small \(x\)
Indeterminate form resolution: \(0^\infty\)

Theorems

Exponential Growth Approximation
Logarithmic Properties
Taylor Series Expansion
L'Hôpital's Rule (optional for further steps)

Suitable Grade Level

Undergraduate Mathematics or Advanced High School (AP Calculus)