Math Problem Statement

Вычислите предел lim_{x->0} (e^(-1/x^2)) / x^100

Solution

The problem is to evaluate the following limit:

limx0e1x2x100\lim_{x \to 0} \frac{e^{-\frac{1}{x^2}}}{x^{100}}

Solution:

  1. Understanding the components of the expression:
    • e1x2e^{-\frac{1}{x^2}}: As x0+x \to 0^+ or x0x \to 0^-, the term 1x2-\frac{1}{x^2} tends to -\infty. Therefore, e1x20e^{-\frac{1}{x^2}} \to 0.
    • x100x^{100}: This term grows to ++\infty as x0+x \to 0^+ and is undefined for x0x \to 0^- due to the even power.

Thus, the numerator approaches 00, while the denominator approaches \infty. This suggests that the overall fraction might approach 00, but we need to formalize this further.


  1. Substitution to simplify: Let y=1xy = \frac{1}{x}. Then, as x0+x \to 0^+, y+y \to +\infty. Rewriting the limit in terms of yy:

    limx0+e1x2x100=limy+ey2(1y)100=limy+y100ey2\lim_{x \to 0^+} \frac{e^{-\frac{1}{x^2}}}{x^{100}} = \lim_{y \to +\infty} \frac{e^{-y^2}}{\left(\frac{1}{y}\right)^{100}} = \lim_{y \to +\infty} y^{100} e^{-y^2}


  1. Analyze the new limit: We now need to evaluate limy+y100ey2\lim_{y \to +\infty} y^{100} e^{-y^2}.

    • y100y^{100}: This term grows polynomially (at a finite rate).
    • ey2e^{-y^2}: This term decays exponentially fast, which dominates any polynomial growth.

    Therefore, the product y100ey20y^{100} e^{-y^2} \to 0 as y+y \to +\infty.


  1. Conclusion: limx0e1x2x100=0\lim_{x \to 0} \frac{e^{-\frac{1}{x^2}}}{x^{100}} = 0

Final Answer:

0\boxed{0}


Would you like a detailed explanation of any step, or do you have further questions? Here are some related problems you might want to explore:

  1. What happens if the exponent in x100x^{100} is changed to xnx^n, where nn is a smaller number?
  2. How does the behavior of e1/x2e^{-1/x^2} differ for x0+x \to 0^+ and x0x \to 0^-?
  3. What if the numerator is e1/x2e^{1/x^2} instead of e1/x2e^{-1/x^2}?
  4. How does the comparison of exponential decay vs polynomial growth work in general limits?
  5. Can this limit be solved using L'Hôpital's Rule, and how would that compare?

Tip: When dealing with limits involving exponentials and polynomials, exponential terms (growth or decay) usually dominate over polynomial terms!

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Math Problem Analysis

Mathematical Concepts

Limits
Exponential Functions
Asymptotic Behavior

Formulas

lim_{x->a} f(x)/g(x)
Substitution for simplification of limits

Theorems

Dominance of exponential decay over polynomial growth

Suitable Grade Level

Undergraduate Calculus