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Mathematics 14 Online
OpenStudy (anonymous):

Question from integral calculus

OpenStudy (anonymous):

OpenStudy (loser66):

let integrand \(x^x=y\) and take log both sides to get exponent down. then proceed the leftover

OpenStudy (anonymous):

Check the integrand . And how will we take logarithms ? If you have solution, please post

OpenStudy (anonymous):

Taking logarithms doesnot help.

OpenStudy (amistre64):

if y = x^x log(y) = x log(x) taking the derivative we get y'/y = log(x) + x/x y' = x^x (log(x) + 1) what do you know of taylor series?

OpenStudy (amistre64):

or, is this one of those problems which lets you know that integrating is not as cut and dry as taking derivatives?

OpenStudy (amistre64):

are you able to work a reimann sum using simpsons, left/right/mid, traps ...

OpenStudy (anonymous):

the integrand is undefined at the lower limit. you have to consider it.

OpenStudy (anonymous):

yes i know about taylor, simpson, riemann, ...

ganeshie8 (ganeshie8):

\[\large e^x = \sum\limits_{n=0}^{\infty}\dfrac{x^n}{n!}\]

ganeshie8 (ganeshie8):

\[\large x^x = e^{x\ln x} = \sum\limits_{n=0}^{\infty}\dfrac{(x\ln x)^n}{n!}\]

ganeshie8 (ganeshie8):

\[\large \int\limits_0^1 x^x ~dx= \int\limits_0^1\sum\limits_{n=0}^{\infty}\dfrac{(x\ln x)^n}{n!}~dx\]

ganeshie8 (ganeshie8):

knw how to handle that beast ?

ganeshie8 (ganeshie8):

http://en.wikipedia.org/wiki/Sophomore's_dream

OpenStudy (amistre64):

i would use right hand triangles, since its not defined at x=0 :) \[\sum_{i=1}^{n} f(a+i\frac{b-a}{n})\frac{b-a}{n}\]

OpenStudy (amistre64):

an + ib -ia (n-i)a + ib since a=0, b=1 sum f(i) 1/n, i = 1 to n sum i^i 1/n, i = 1 to n something like that if memory serves

OpenStudy (anonymous):

so what should be the final answer? Will we keep in summation notation only?

ganeshie8 (ganeshie8):

from that wiki link :\[\large \int\limits_0^1 x^x ~dx = -\sum\limits_{n=1}^{\infty} (-n)^{-n} \approx 0.78343\] which is some constant like e, however we don't know whether that constant is irrational like e

OpenStudy (anonymous):

However, is there any way of solving this problem, using numerical analysis? If yes, please let me know... The solution is very nice .

ganeshie8 (ganeshie8):

if u just want to approximate, try riemann sum ?

ganeshie8 (ganeshie8):

or any other fancy numerical technique tha tu knw

ganeshie8 (ganeshie8):

try this in matlab : ``` fun = @(x) x.^x; q = quadcc(fun,0,1) ```

OpenStudy (amistre64):

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