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MeepiBest ResponseYou've already chosen the best response.0
Do you know how to use integration by parts?
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
Integration by parts doesn't look nice..
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
\[\int \frac{dx}{lnx} = \frac{x}{lnx}  \int x d(\frac{1}{lnx})\]If that's what you meant...
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
u=lnx; x=e^u du=dx/x x du = dx \[\int \frac{1}{u}e^u~du\] maybe?
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
http://www.wolframalpha.com/input/?i=integrate+1%2Flnx you sure you got it right?
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
\[\int \frac{dx}{lnx}\]\[=\int \frac{x}{xlnx}dx\]\[=\int \frac{x}{lnx}d(lnx)\]\[=\int \frac{e^{lnx}}{lnx}d(lnx) \]\[=\int \frac{e^u}{u}du\]\[=\int \frac{1}{u}d(e^u)\].... The original question is \[y' = \frac{1}{y^2lnx}\]\[y^2 dy = \frac{dx}{lnx}\]I supposed integrating both sides can give me the answer :/
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
Perhaps I'm in the wrong direction?!
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
it looks like any solution will have to run into a logramathic integral
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
What technique(s) is(are) required to solve this equation?
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
ones that i havent run into yet :/
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
you can try to develop a series poly for it, and see what that would bring you
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
:O I haven't learnt expanding the function!
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
what methods have you learnt?
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
separable, integrating factors, exact question, undetermined coefficients, variation of parameters, homogeneous equation... Btw, I just ran around and grabbed the exercise, I think it's not in my textbook :/ http://ocw.mit.edu/courses/mathematics/1803differentialequationsspring2010/readings/notes_exe/MIT18_03S10_1ex.pdf 1A3a
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
y^2 y' = 0 when y'=0 or y^2=0; given y1=0 and y2=C not sure of a wronskian would be useful here or not
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
Actually, how does Wronskian work. I just know it can determine the linear dependency.. Then, nothing :/
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
the wronskian is the short version of the undetermined coeffs
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
Wx W Wy f1 0 f2 f'1 g f'2 then its similar to the cross product W = f1f'2  f'1f2 Wx = g f2 Wy = f1 g and you integrate Wx/W and Wy/W
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
yeah, i dont see it being useful here tho
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
It...somehow... reminds me of Cramer's :/
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
it is, since the cramer is what you do at the end of the undetermined coeffs
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
Ahhhh.... Thanks for teaching something new though!!!
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
*teaching me something
 one year ago

amistre64Best ResponseYou've already chosen the best response.2
yep, but as far as a solution to this goes; i got no idea. The wolf says we need a logartithmic integral which leads me to believe that this might be workable with a power series solution; but i dont think i can think thru it this late
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
Never mind, perhaps i should ask my teacher after the lesson today. I have to go for lesson now. Once again, thanks for your help!!
 one year ago

RolyPolyBest ResponseYou've already chosen the best response.0
Sorry for the very late reply. I asked my teacher some days ago and he said I wouldn't know how to do it. Even for some graduate student, they didn't know that too. And he didn't teach me how to do the integration.... Thanks for your time helping me out!!
 one year ago
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