Don't hide your solutions.

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- October 8th 2011, 08:47 PMRandom Variableintegrals
Don't hide your solutions.

1)

2)

3) - October 10th 2011, 05:06 PMUnbeatable0Re: integrals
Nice problems!

(1) can be written as

The first integral is known and its value is . The second can be calculated with contour integration, yielding .

(3) note that

and since for , we can put to obtain:

Also note that and .

From all these we obtain:

and when is a natural number, this is

(2) Let , with .

Then , and we're looking for this integral, evaluated when , .

To calculate , note that:

So that:

Now let .

It is easily checked that the indefinite integral with respect to of the right hand side of the previous equation is , so:

From the definition of it is obvious that the left hand side vanishes when , so the right hand side also vanishes. Thus, using , we get . Therefore:

Now we differentiate with respect to , remembering that :

.

Now, as we noted, , so finally we have:

.

Fortunately, when and the second term vanishes, and thus

- October 10th 2011, 08:12 PMRandom VariableRe: integrals
Surprisingly, problem 2 can also be solved by integrating by parts.

- December 13th 2011, 02:47 PMuniquesailorRe: integrals
This another Solution :

https://sites.google.com/site/atzahr...xample1sol.png