What does it mean to have an integral with a lower bound of infinity?

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SUMMARY

The discussion centers on evaluating an integral with bounds from negative infinity to zero for an even function, specifically f(y) = f(-y). The user correctly applies the property of integrals, stating that \(\int_a^b f(x) dx = -\int_b^a f(x) dx\), confirming its validity even when the bounds include infinity. By taking the limit to infinity rather than negative infinity, the user successfully concludes their proof, demonstrating a solid understanding of integral properties in calculus.

PREREQUISITES
  • Understanding of integral calculus, particularly properties of definite integrals.
  • Familiarity with even functions and their symmetrical properties.
  • Knowledge of limits and their application in calculus.
  • Experience with manipulating infinite bounds in integrals.
NEXT STEPS
  • Study the properties of even and odd functions in calculus.
  • Learn about improper integrals and their convergence criteria.
  • Explore advanced techniques for evaluating integrals with infinite bounds.
  • Review the concept of limits in the context of integrals, particularly with respect to infinity.
USEFUL FOR

Students of calculus, mathematicians, and anyone involved in mathematical proofs or analysis of integrals, particularly those dealing with infinite bounds.

dmatador
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I am working on a proof in which I have an integral with bounds negative infinity to zero, with an even function, i.e., f(y) = f(-y). I took the limit to infinity rather than negative infinity since y is negative (which is OK I think) but now I have an integral that goes from infinity to 0. What can I make of this? I remember something about this from calculus, but nothing in particular.
 
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dmatador said:
I am working on a proof in which I have an integral with bounds negative infinity to zero, with an even function, i.e., f(y) = f(-y). I took the limit to infinity rather than negative infinity since y is negative (which is OK I think) but now I have an integral that goes from infinity to 0. What can I make of this? I remember something about this from calculus, but nothing in particular.
\int_a^b f(x) dx = -\int_b^a f(x) dx
 
So this holds even when a or b is infinity? If so, thanks for the help. My proof is done.
 

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