Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing

This Question is Closed

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
How to start?
 2 years ago

Meepi Group TitleBest ResponseYou've already chosen the best response.0
Do you know how to use integration by parts?
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
Integration by parts doesn't look nice..
 2 years ago

RolyPoly Group TitleBest 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...
 2 years ago

amistre64 Group TitleBest 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?
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
http://www.wolframalpha.com/input/?i=integrate+1%2Flnx you sure you got it right?
 2 years ago

RolyPoly Group TitleBest 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 :/
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
Perhaps I'm in the wrong direction?!
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
it looks like any solution will have to run into a logramathic integral
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
What technique(s) is(are) required to solve this equation?
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
ones that i havent run into yet :/
 2 years ago

amistre64 Group TitleBest 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
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
:O I haven't learnt expanding the function!
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
what methods have you learnt?
 2 years ago

RolyPoly Group TitleBest 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
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
*exact equation lol
 2 years ago

amistre64 Group TitleBest 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
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
Actually, how does Wronskian work. I just know it can determine the linear dependency.. Then, nothing :/
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
the wronskian is the short version of the undetermined coeffs
 2 years ago

amistre64 Group TitleBest 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
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
yeah, i dont see it being useful here tho
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
It...somehow... reminds me of Cramer's :/
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.2
it is, since the cramer is what you do at the end of the undetermined coeffs
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
Ahhhh.... Thanks for teaching something new though!!!
 2 years ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
*teaching me something
 2 years ago

amistre64 Group TitleBest 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
 2 years ago

RolyPoly Group TitleBest 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!!
 2 years ago

RolyPoly Group TitleBest 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
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.