Integrating from - to + infinity

In summary, integrating a function from negative to positive infinity involves using the method of limits to find the total area under a curve that extends infinitely in both directions. This can be useful in various applications, but not all functions can be integrated in this way. The properties of integrals, such as symmetry, can also aid in the integration process. The difference between integrating from negative to positive infinity and from 0 to positive infinity lies in considering the entire domain versus only the positive portion of the function. It is important to consider the appropriate domain when evaluating an integral.
  • #1
terp.asessed
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Homework Statement


I am having trouble integrating ∫ (x = -∞ to +∞) x3e-αx2 dx part--is this 0 or 1/α2? And, could someone explain? I am pretty sure that, when

∫ (x =0 to +∞) x3e-αx2 dx = 1/α2

However, with x = -∞ to +∞, and the function of the equation being odd, I am lost.

Homework Equations


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The Attempt at a Solution


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  • #2
It's zero because, like you noted, the integrand is odd.
 

FAQ: Integrating from - to + infinity

How do you integrate a function from negative to positive infinity?

To integrate a function from negative to positive infinity, you can use the method of limits. This involves taking the limit as the upper bound of integration approaches positive infinity. If this limit exists, then the integral converges and can be evaluated. Otherwise, the integral diverges.

What is the significance of integrating from - to + infinity?

Integrating from negative to positive infinity is a way to find the total area under a curve that extends infinitely in both directions. This can be useful in various mathematical and scientific applications, such as calculating the total charge or energy in a system.

Can all functions be integrated from negative to positive infinity?

No, not all functions can be integrated from negative to positive infinity. The function must satisfy certain conditions, such as being continuous and bounded, in order for the integral to converge. If these conditions are not met, then the integral will diverge.

How can you use the properties of integrals to integrate from - to + infinity?

One property that can be useful for integrating from negative to positive infinity is the symmetry property. If a function is even (symmetric about the y-axis), then the integral from negative to positive infinity is equal to twice the integral from 0 to positive infinity. This can make the integration process easier.

What is the difference between integrating from - to + infinity and from 0 to + infinity?

Integrating from negative to positive infinity considers the entire domain of a function, while integrating from 0 to positive infinity only looks at the positive portion of the function. This can make a difference in the value of the integral, as well as the convergence or divergence of the integral. It is important to consider the appropriate domain when evaluating an integral.

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