What to take as p(x,y) and q(x,y) with partials

[prace]

http://album6.snapandshare.com/3936/45466/845529.jpg

 

[Fermat]

Your DE is P(x,y)dx + Q(x,y)dy = 0 and you want to find out if it is exact.

The equation will be exact if $$\frac{\partial P}{\partial y} = \frac{\partial Q}{\partial x}$$.

You have P(x,y) = 5x + 4y giving $$\frac{\partial P}{\partial y}=4$$

And Q(x,y) = 4x - 8y² giving $$\frac{\partial Q}{\partial x} = 4$$

Have a look at http://www.sosmath.com/diffeq/first/exact/exact.html" and see if it helps.

 

[prace]

Great, I took a quick glance at the sight and it looks as if that will help a lot. I will have to take a deeper look into it later this afternoon, but I just wanted to say thanks for your imput. I'll let you know if I have any more problems. =p

thanks! ^_^