# Ordinary Differential Equations!Urgent Help Neede

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• Jun 13th 2008, 10:44 AM
noob
Quote:

Originally Posted by Isomorphism
Yes you can.

You mean "integrating factor"? There is no need for it here, since the differential equation is in separable form..

yup, what i mean is an "integrating factor"..so we only no need to consider the integrating factor when the differential equation is in separable form huh?thanks mates..really2 thanks (Nod)

i will come out with my final solution for question 1 first (still need a help in question 2 afterwards)

p/s: you are a lecturer or tutor maybe huh? sorry for off topic
• Jun 13th 2008, 10:47 AM
Isomorphism
Quote:

Originally Posted by noob
p/s: you are a lecturer or tutor maybe huh? sorry for off topic

Well... not yet (Rofl)
• Jun 14th 2008, 11:08 AM
noob
Quote:

Originally Posted by noob
Hye all, as a newbie in this forum, i would be really sorry if got any mistake or indirectly breaching the terms and condition in this forum.

I'm just really2 need a help from anyone of you, please helping me to attain the solution of both questions. The question is on Ordinary Differential Equations topic. This is my important assignment question as it will bring 15% of my career marks (continuous assessment) before final exam. Please really help as that 15% is too important to me..thanks in advanced mates (Crying)

http://i270.photobucket.com/albums/j...untitled-5.jpg

Hye again..thanks again for all your instruction, im done with no 1..now it is no 2 question

after differentiate with respect to x i obtain

$y''+ 2xy'+2y$

thus,how can i get the characteristic equation (as the initial step of using variation of parameter method) from that equation since got two variables which is x and y;

$m^2+2xy+2$

anybody help??thanks in advance

i thought is it we need to separate those x??
• Jun 14th 2008, 03:53 PM
Chris L T521
Quote:

Originally Posted by noob
thank you very much, from the question needed, is it i can left the answer just like this??one more things that quite confusing me is when did we need to consider the integral factor?? some question in book using an integral factor method

Read [in particular] post #2 (integrating factor) and #8 (variation of parameters) in my Differential Equations Tutorial. This may help with future problems.
• Jun 14th 2008, 08:07 PM
noob
Quote:

Originally Posted by Chris L T521
Read [in particular] post #2 (integrating factor) and #8 (variation of parameters) in my Differential Equations Tutorial. This may help with future problems.

i know how to use the method of variation of parameter, the problem now is how can i attain the characteristic equation since got two variables (as my previous post)..could u please help me to find it
• Jun 14th 2008, 09:13 PM
Chris L T521
Quote:

Originally Posted by noob
Hye again..thanks again for all your instruction, im done with no 1..now it is no 2 question

after differentiate with respect to x i obtain

$y''+ 2xy'+2y$

thus,how can i get the characteristic equation (as the initial step of using variation of parameter method) from that equation since got two variables which is x and y;

Quote:

Originally Posted by noob
i know how to use the method of variation of parameter, the problem now is how can i attain the characteristic equation since got two variables (as my previous post)..could u please help me to find it

Well, if the equation was $x^2\frac{d^2y}{dx^2}+2x\frac{dy}{dx}+2y=0$ then the DE has the form of a Cauchy-Euler Equation and a characteristic equation could be easily found.

However, that's not the case. Also, Mathematica and the TI-89 tell me there is no solution to the DE...(Thinking)
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