Math Problem Statement

Evaluate the integral \( \int_1^\infty e^{-x^2} \, dx \) and indicate whether it is divergent or convergent.

Solution

The image asks to evaluate the integral

1ex2dx\int_1^\infty e^{-x^2} \, dx

and determine whether it is divergent or convergent.

Evaluation:

The integral of the Gaussian function ex2e^{-x^2} over a finite interval is not solvable in terms of elementary functions. However, for limits that extend to infinity, it’s useful to understand the behavior of the function.

Convergence:

The integrand ex2e^{-x^2} decays very rapidly as xx \to \infty, because as xx increases, ex2e^{-x^2} approaches 0 extremely quickly. To determine whether the integral converges, we can analyze the improper integral:

1ex2dx\int_1^\infty e^{-x^2} \, dx

Since ex2e^{-x^2} decays faster than any polynomial as xx \to \infty, this integral converges. A similar integral over (,)(-\infty, \infty), known as the Gaussian integral, is known to converge, and thus, this integral also converges on [1,)[1, \infty).

Conclusion:

The integral 1ex2dx\int_1^\infty e^{-x^2} \, dx converges.

Would you like me to go into more details or have any questions?

Here are 5 related questions to expand your knowledge:

  1. How would you evaluate the Gaussian integral over the entire real line?
  2. Can you express 0ex2dx\int_0^\infty e^{-x^2} \, dx using known special functions?
  3. How do you determine the convergence of an improper integral?
  4. What techniques can be used to evaluate integrals that involve exponential decay?
  5. What role does the error function erf(x)\text{erf}(x) play in integrals involving ex2e^{-x^2}?

Tip: When dealing with improper integrals, it's essential to assess the behavior of the function at the limits of integration (e.g., as xx \to \infty or at singular points).

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Math Problem Analysis

Mathematical Concepts

Calculus
Improper Integrals
Exponential Decay

Formulas

\( \int e^{-x^2} \, dx \)

Theorems

Convergence of Improper Integrals
Gaussian Integral

Suitable Grade Level

Undergraduate Mathematics