Richard Feynman's Integral Trick

You may use integration by parts if you like :

\(\displaystyle \displaystyle\lim_{N \to \infty}\int_0^Nze^{-z}dz \)


After you do the work (and show the work) after this, you should get the equivalent of:


\(\displaystyle \displaystyle\lim_{N \to \infty}\bigg(\dfrac{-z - 1}{e^z}\bigg)\bigg|_0^N\)


Then you need to evaluate this and show the work.
 
… Is it correct to use Richard Feynman's Integral Trick instead of integration by parts … [?]
Without context, how could anyone answer your question about a "correct" method?

Is this a homework exercise? Were you instructed to use a particular method?
 
Hello every one

Is it correct to use
Richard Feynman's Integral Trick instead of integration by parts to find the integral below:

View attachment 10617

Thanks

Whether it's correct to use the method depends on the assignment; but it looks like valid work (and a relatively simple application of differentiation under the integral). And it does give the same result.

Is there a particular reason you were unsure? Is there a reason you wanted to use this method instead of parts?
 
Whether it's correct to use the method depends on the assignment; but it looks like valid work (and a relatively simple application of differentiation under the integral). And it does give the same result.

Is there a particular reason you were unsure? Is there a reason you wanted to use this method instead of parts?

I did not now this method before. It is knew for me, I learned to use it for integrating
x2exp(-x2).

So I was thinking to try to use it instead of integration by parts.
But it seems so easy and it looks weired to differentiate with respect to a which is a constant and then assume it equals to 1!
 
I did not now this method before. It is knew for me, I learned to use it for integrating
x2exp(-x2).

So I was thinking to try to use it instead of integration by parts.
But it seems so easy and it looks weired to differentiate with respect to a which is a constant and then assume it equals to 1!

It's new to me, too! If I've seen it before, I've never used it; so I can't tell you any more about when it is most appropriate, or how to develop skill at using it. But it is very interesting, isn't it?

Integration tends to be like this, an "art" rather than a routine process, in which you have a large collection of "tools" available, and can choose whatever tools you think might help.
 
It's new to me, too! If I've seen it before, I've never used it; so I can't tell you any more about when it is most appropriate, or how to develop skill at using it. But it is very interesting, isn't it?

Integration tends to be like this, an "art" rather than a routine process, in which you have a large collection of "tools" available, and can choose whatever tools you think might help.

Yes it is a very interesting trick! Thanks a lot :)
 
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