Hi,

Need to solve the following equation, but i can't seem to separate the variables correctly so i can integrate through.

dx/dt = t - x

cheers

Oli

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- January 11th 2008, 06:14 AMolipSeparation of variables
Hi,

Need to solve the following equation, but i can't seem to separate the variables correctly so i can integrate through.

dx/dt = t - x

cheers

Oli - January 11th 2008, 06:19 AMcolby2152
This is a non-homogeneous differential equation.

You have to guess an initial solution for . Check this out: Method of undetermined coefficients - Wikipedia, the free encyclopedia - January 11th 2008, 06:33 AMKrizalid
- January 11th 2008, 06:25 PMmr fantastic
- January 12th 2008, 06:16 AMolip
Hi,

thanks for all help so far, that working makes sense to me Krizalid, but on integrating i get i.e. , or , which doesnt seem right to me.

I should give more information. This was just part of some dynamics book and i couldn't figure out how they got the solution. Their solution was

where is the solution at t=0

thanks again,

Oli - January 12th 2008, 01:47 PMolip
Hi again,

realised i made a lazy mistake there, forgot to add in the constant of integration, so the solution actually becomes

When i substitute this back in to the original equation it works, which is good, however it is different than the solution given in the book:

which doesn't give the right answer when substituted back into the equation. Is the one in the book wrong?? I am confused!

cheers,

Oli - January 12th 2008, 06:09 PMmr fantastic