Can the Convergence of Taylor Series

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SUMMARY

The discussion centers on the convergence of the integral \(\int_{0}^{1} f(x) g(x) \, dx\) when \(g(x)\) can be expressed as a Taylor series that converges for \(|x| < 1\). It concludes that the integral can be represented as \(\int_{0}^{1} f(x) \sum_{n=0}^{\infty} a_{n} x^{n} \, dx\) despite the series not converging at \(x=1\). The key point is that the behavior at a single point does not affect the convergence of the integral, provided the integral's definition is consistent with measure theory principles.

PREREQUISITES
  • Understanding of Taylor series expansions
  • Knowledge of definite integrals and their properties
  • Familiarity with measure theory concepts
  • Basic calculus skills, particularly in integration
NEXT STEPS
  • Study the properties of Taylor series and their convergence criteria
  • Explore the definitions of definite integrals in measure theory
  • Investigate examples of integrals involving singularities and their convergence
  • Learn about the implications of pointwise convergence versus uniform convergence in integration
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Mathematics students, particularly those studying calculus and analysis, as well as educators looking to deepen their understanding of integration and series convergence.

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Homework Statement


If \int_{0}^{1} f(x) g(x) \ dx converges, and assuming g(x) can be expanded in a Taylor series at x=0 that converges to g(x) for |x| &lt; 1 (and perhaps for x= -1 as well), will it always be true that \int_{0}^{1} f(x) g(x) \ dx = \int_{0}^{1} f(x) \sum_{n=0}^{\infty} a_{n} x^{n} \ dx?

Will the fact that that the series doesn't converge for x=1 ever be an issue?

A couple of examples are \int_{0}^{1} \frac{f(x)}{1-x} \ dx = \int_{0}^{1} f(x) \sum_{n=0}^{\infty} x^{n} \ dx and \int_{0}^{1} f(x) \ln(1-x) \ dx = -\int_{0}^{1} f(x) \sum_{n=1}^{\infty} \frac{x^{n}}{n} \ dx.

Homework Equations

The Attempt at a Solution


I want to say that it will always be true since it's just a single point. But I don't know if that's sufficient justification.
 
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Is the sum really inside the integral? If yes: the integral (by definition) does not care about the function value at 1 at all.
If it is outside, it gets more interesting.
 
What kind of integration has been defined in this analysis course? What definition of a definite integral is used? Are you studying measure theory?
 

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