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 Aug12 revised Some exponential integrals - I need algebraical solution besides my graphical one added 248 characters in body Aug12 revised Some exponential integrals - I need algebraical solution besides my graphical one added 248 characters in body Aug12 asked Some exponential integrals - I need algebraical solution besides my graphical one Aug9 accepted Need some algebra explaination for hyperbolic sinus Aug9 asked Need some algebra explaination for hyperbolic sinus Aug2 accepted Trigonometric functions Aug2 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... Aug2 asked Trigonometric functions Aug2 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? Aug2 comment Short integral question @DonAntonio but i am using a Google Chrome it is the best :) Aug1 accepted Short integral question Aug1 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. Aug1 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. Aug1 comment Short integral question I downvoted noone ... Aug1 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. Aug1 comment Short integral question But $x\neq y$ :((( It never will be. I don't understand... Aug1 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? Aug1 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... Aug1 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. Aug1 comment Short integral question I mean we usualy did like this: $\frac{d}{dx}\sin\left(x^2\right) = \underbrace{\cos\left(x^2\right)}_{\frac{d}{dx}\sinqleft(x^2\right)} \cdot \underbrace{2x}_{\rlap{\text{derivative of what is inside the bracket}}}$ The Wolfram alpha confirms it wolframalpha.com/input/?i=d%2Fdx%20%5Csin(x%5E2)&t=crmtb01