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  • 0 posts edited
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  • 54 votes cast
Aug
12
comment Some exponential integrals - I need algebraical solution besides my graphical one
I would like to analytically show, that they equal 0. Check my Edited Question. I was thinking to solve them using the relation described there, but i get spapped limits and a negaitve sign... Long story short, I need to know what are the relations between $$\int\limits_{0}^{\infty} dx \qquad \int\limits_{0}^{-\infty} dx \qquad \int\limits_{\infty}^{0} dx \qquad \int\limits_{-\infty}^{0}$$
Aug
12
revised Some exponential integrals - I need algebraical solution besides my graphical one
added 248 characters in body
Aug
12
revised Some exponential integrals - I need algebraical solution besides my graphical one
added 248 characters in body
Aug
12
asked Some exponential integrals - I need algebraical solution besides my graphical one
Aug
9
accepted Need some algebra explaination for hyperbolic sinus
Aug
9
asked Need some algebra explaination for hyperbolic sinus
Aug
2
accepted Trigonometric functions
Aug
2
comment Trigonometric functions
Yes. I need to know how to get RHS out of LHS. I tried to use the double angle trigonometric identity and it only got more complicated...
Aug
2
asked Trigonometric functions
Aug
2
comment Short integral question
I think i understand everything now exept this: $\left.-\pi\int\limits_0^\infty(-2r\,dr)e^{-r^2}=-\pi e^{-r^2}\right|_0^\infty$ How do you do this?
Aug
2
comment Short integral question
@DonAntonio but i am using a Google Chrome it is the best :)
Aug
1
accepted Short integral question
Aug
1
comment Short integral question
I upvoted all of you (I hope it helps). This wouldn't be the first time this happened. This page is somehow bugged it seems.
Aug
1
comment Short integral question
Oh i did ... But i didn't know. It happened because this page is jumping up and down while those advertisments are loading. I fixed the downvote.
Aug
1
comment Short integral question
I downvoted noone ...
Aug
1
comment Short integral question
Thank you for this explaination and I am sorry but this $e^x$ function ... I hate it at the moment. Really. Maybee I ll have more questions.
Aug
1
comment Short integral question
But $x\neq y$ :((( It never will be. I don't understand...
Aug
1
comment Short integral question
So I calculated $\int xe^{-x^2/a} dx$ in Wolfram alpha and I can see that the chain rule has been aplied corectly ( wolframalpha.com/input/?i=int+x*e%5E%7B-x%5E2%2Fa%7D ) because what i got is $-\frac{a}{2}e^{-x^2/a}$. So why wouldn't a chain rule work if I only remove $x$? Mathematics fails?
Aug
1
comment Short integral question
This is wrong: $\left(\int\limits_{-\infty}^\infty e^{-x^2}dx\right)^2=\int\limits_{-\infty}^\infty e^{-x^2}dx\int\limits_{-\infty}^\infty e^{-y^2}dy$ How come you use $y$ in place of $x$... I cant just write 2x = 2g...
Aug
1
comment Short integral question
OMG i wrote my equation a bit wrong and now the "X" mark to edit it is behind the right margin of this webpage. I can't edit... ADMIN PLEASE HELP.