the part is h=1/sqrt(2y^2-1) sorry..

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- Mar 8th 2008, 06:17 PM #1

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## ODE help

Hi..i got this equation (2xy^2 - x)dx + (x^2y - y)dy=0 ;I know its not exact as i ve partially differentiated it to get M=4xy(wrt y) and N= 2xy(wrt x) After multipying it by h(y)..i got h= i/sqrt(2y^2-1)..after that i cant prove that its exact..can someone please give me a lead on this..

- Mar 8th 2008, 06:18 PM #2

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- Mar 9th 2008, 01:34 AM #3

- Mar 9th 2008, 01:46 AM #4

- Mar 9th 2008, 03:34 AM #5

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## Differential equation

I try to solve this differential equation as:

You have to find for z = z(x,y) and solve this DE:

This DE can be solved only by numerical approach; it is very difficult solve because when you differentiate Q you get something ugly to calculate. Note:

if would be**exact**and it would be very simple to solve. How to manipulate this equation they would be exact- insert:

- Mar 9th 2008, 03:46 AM #6

- Mar 9th 2008, 04:25 AM #7

- Mar 9th 2008, 05:37 AM #8

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Dear mr fantastic.

Only problem is that this is differential equation and not integral equation.

When you have problem like

you integrate in both sides. When you can do this is**only**when differential equation is linear and homogen that is when is satisfy

Most important is when you calculate something you have to have very good theoretical background !

Think about that.

- Mar 9th 2008, 05:42 AM #9

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- Mar 9th 2008, 05:45 AM #10

- Mar 9th 2008, 07:33 AM #11

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Dear mr fantastic

I would be very PLEASED if you calculate that DE and show it to me. However when you do any step of calculations I would be very happy to tell me from where it comes from and also any lemma, definition, statement and theorem you used to calculate that DE.**That I very important in mathematics as you already know**.

Good luck.

- Mar 9th 2008, 07:51 AM #12

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- Mar 9th 2008, 11:53 PM #13

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## reply

well..so which is which?the separable one sounds easy and i manage to do it but i did learn that if the dfq is not exact, we have to multiply it by the Integrating factor to make it exact which I tried but its too difficult..someone pls give me the confirmed way to approach it...im starting to get confused..

- Mar 10th 2008, 12:14 AM #14

- Mar 10th 2008, 12:38 AM #15