still cant beak it as one type of variable on each side

so i substitute by another variable

i dont know how to separate each variable type on one side

so i could integrate

??

Printable View

- Aug 16th 2009, 01:06 PMtransgalacticvariable substitution question(diff)

still cant beak it as one type of variable on each side

so i substitute by another variable

i dont know how to separate each variable type on one side

so i could integrate

?? - Aug 16th 2009, 05:53 PMsongoku
Hi transgalactic

Do you know integrating factor ? :) - Aug 16th 2009, 09:05 PMtransgalactic
yes i know that.but how did you know that that i should solve it like this in here?

- Aug 16th 2009, 09:12 PMChris L T521
- Aug 16th 2009, 10:14 PMtransgalactic
ok i rearanged it like i used to in order to find integration factor

i got that the integration factor is:

so i mltiply both sides by y

now its even more complicated than before

?? - Aug 16th 2009, 11:14 PMsongoku
Hi transgalactic

Sorry, I have tried to solve this and ended up finding the integration that can't be stated in elementary function. (Doh)

For now, maybe we can wait for Chris L T521's help (Smile) - Aug 16th 2009, 11:46 PMtransgalactic
this is a fll solution:

http://i30.tinypic.com/2lllrpk.gif

its really frustrating that i did all the things by the book and i didnt manage to solve its

what is the mistake in diagnozing the wa of solution

what should step there in my equation is a red light to solve it like

the solution above? - Aug 16th 2009, 11:54 PMsongoku
Hi transgalactic

I re-check your work and find out the mistake.

-----------> you missed the term "t"

So, that's not linear form anymore but Bernoulli form :) - Aug 17th 2009, 12:21 AMtransgalactic

i dont have here a bernuly equation ..

what to do?

bernule needs to have f'() form

i dont know how transform it to this form - Aug 17th 2009, 12:31 AMsongoku
Hi transgalactic

- Aug 17th 2009, 12:51 AMtransgalactic
here is another problem:

all those variable are confusing

how did you know to t it in this way

dt/dz

or

dz/dt

why you put the derivative part in that way

what is the logic behind it

? - Aug 17th 2009, 01:06 AMsongoku
Hi transgalactic

It's not matter whether you solve or because it will give you the same result.

If you state it in , it will be :

Can you solve it ? :) - Aug 17th 2009, 01:08 AMtransgalactic
the problem is that i cant see what variable is a function of what variable

if i had dy and dx

then i whould do

dy/dx

but here dz and dt

i dont know who is more superior - Aug 17th 2009, 01:12 PMChris L T521
- Aug 17th 2009, 08:13 PMsongoku
Hi Chris L T521 and transgalactic

@ Chris L T521:

There is error in OP's work. :)

@transgalactic :

Example :

If you re-arrange the question :

You will have same result. So, it doesn't matter if you solve or