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Having trouble understanding a question (differential equations) watch

1. Hi , I'm not too sure what to do for the below question.

Do I put x=3 and y=0 for the first equation, then x=18 and y=0? I can't seem to understand on how to start as I can't find any examples.
2. (Original post by kerrypop)
Hi , I'm not too sure what to do for the below question.

Do I put x=3 and y=0 for the first equation, then x=18 and y=0? I can't seem to understand on how to start as I can't find any examples.
Put y=0 and arrange the equation

Integrate and find x=f(t)
3. (Original post by ztibor)
Put y=0 and arrange the equation

Integrate and find x=f(t)

I still don't really understand what is going on. If I integrate it I should get my answer, what does that mean in terms of the question though?
4. (Original post by kerrypop)

I still don't really understand what is going on. If I integrate it I should get my answer, what does that mean in terms of the question though?
For the LHS

With partial fractions

So
A=B and 12A=1 -> A=B=1/12

You will get the value of c from the initial conditions t=0 -> x_0=3 or 18
5. (Original post by ztibor)
For the LHS

With partial fractions

So
A=B and 12A=1 -> A=B=1/12

You will get the value of c from the initial conditions t=0 -> x_0=3 or 18
Thanks, that has been really helpful

I can see by using

I can get to the same answer as you do.

Could you please explain how you started with as my algebra isn't that great and I can't see how you got it.
6. (Original post by kerrypop)
Thanks, that has been really helpful

I can see by using

I can get to the same answer as you do.

Could you please explain how you started with as my algebra isn't that great and I can't see how you got it.
Separation of variables.

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Updated: January 22, 2014
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