Very hard differential equation. Help please please :(
Favorites|Homepage
Subscriptions | sitemap
HOME > > Very hard differential equation. Help please please :(

Very hard differential equation. Help please please :(

[From: ] [author: ] [Date: 12-07-11] [Hit: ]
if you are careful, you can use integration by parts, which is what sort of looks like what you are doing.Thats the farthest I can take you.But I would suggest try doing integration by parts- with remembering that you need to integrate with respect to x.Hope this helps.......

Multiply equation (2) by the integrating factor 1/x^4
dv/dx (1/x^4) - 4v /x5= 8/x^3 -----------------(3)
The left-hand side is the derivative of v /x^4 or (v/x^4) '
(3) becomes
(v/x^4)' = 8/x^3
Integrate both sides

v / x^4 = ∫ 8/x^3 dx + C
v/x^4 = -4/x^2 + C
v = -4x^2+Cx^4
v= Cx^4-4x^2

substitute v=y^2

y^2 = Cx^4-4x^2
y = +/- sqrt [ Cx^4-4x^2]

-
I'm scared of math now

-
I gave your question some thought, and here is what I came up with. I don't know if this is the method you NEED to use, but it might be a little easier than what you are doing.

What I did was add xydy to both sides of the equation giving me (and I distributed the 2 on the LHS):

(4x^2 + 2y^2)dx = xy dy

Then I divided both sides by xy to get the dy term by itself.

[(4x^2 + 2y^2)dx] / xy = dy

Then divided everything by dx both sides. This gives us something that looks a little more familiar:

dy/dx = (4x^2 + 2y^2) / xy

Now the major problem is the xy term, but if you think about it, it's the same thing as saying:

(4x^2 + 2y^2) * 1/xy

From there, if you are careful, you can use integration by parts, which is what sort of looks like what you are doing.

That's the farthest I can take you. But I would suggest try doing integration by parts- with remembering that you need to integrate with respect to x.

Hope this helps.
12
keywords: differential,equation,hard,Help,Very,please,Very hard differential equation. Help please please :(
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .