Using comparison theorem to show if an integral is convergent or divergent

In summary, the use of the comparison theorem can be applied to show that the integral of e^(-x^2) from 0 to infinity is convergent. This can be done by comparing it to a larger integral, such as e^(-x), which is known to converge.
  • #1
spaniks
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Homework Statement


use the comparison theorem to show that the integral of e^(-x^2) from 0 to infinity is convergent.

Homework Equations


None

The Attempt at a Solution


In class we have never dealt with using the comparison theorem with the exponential function so I was not sure what I function I would compare it to in order to solve this problem. Could I compare it to something like e^(-x)?
 
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  • #2
spaniks said:

Homework Statement


use the comparison theorem to show that the integral of e^(-x^2) from 0 to infinity is convergent.


Homework Equations


None

The Attempt at a Solution


In class we have never dealt with using the comparison theorem with the exponential function so I was not sure what I function I would compare it to in order to solve this problem. Could I compare it to something like e^(-x)?

Sure. Just show that is a larger integral which converges.
 

FAQ: Using comparison theorem to show if an integral is convergent or divergent

How does the comparison theorem work?

The comparison theorem for integrals states that if two functions have the same behavior near a given point, and one is integrable while the other is not, then the integral of the first function must also be integrable.

Can the comparison theorem be used to prove both convergence and divergence of an integral?

Yes, the comparison theorem can be used to prove both convergence and divergence of an integral. If the integrals of two functions can be compared, and one is known to converge while the other diverges, then the same must be true for the original integral.

What is the purpose of using the comparison theorem?

The comparison theorem is a powerful tool in determining the convergence or divergence of an integral. It allows us to compare a given integral to a known integral and make conclusions about its behavior without having to evaluate the integral directly.

Are there any limitations to using the comparison theorem?

Yes, there are some limitations to using the comparison theorem. It can only be used when the functions being compared have the same behavior near a given point. It also cannot be used if the functions have different behaviors at the endpoints of the interval of integration.

Can the comparison theorem be used for improper integrals?

Yes, the comparison theorem can be used for improper integrals. As long as the functions being compared have the same behavior near the point of integration, the comparison theorem can be applied to determine the convergence or divergence of the improper integral.

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