I'm really having trouble with this, I can't even understand the example in my textbook. The example problem is:(adsbygoogle = window.adsbygoogle || []).push({});

Show that ydx + xdy + 4dz is exact and then evaluate it over some limits.

I can show that its exact, and once I find the function, I can evaluate it, so I really just need help getting the function. So the book says:

df/dx = y; df/dy = x; df/dz = 4; I understand this part, then the next step is:

f(x,y,z) = xy + g(y,z); Got this too, but now the fun begins. The next line is:

df/dy = x + dg/dy = x or dg/dy = 0; I have no idea what they're talking about here. Where is the dg/dy from? And why is 'x' what the equation is supposed to equal? The next step is:

f(x,y,z) = xy + h(z); followed by:

df/dz = 0 + dh/dz = 4 or h(z) = 4z + C; Again, I have no idea where the dh/dz if from. Also, above df/dz = 4, now it is 0? I understand that if you differentiate 4, you get 0, but what's with the discrepancy?

Any help is appreciated! I know this is long so thanks for your time

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Help with conservative line integrals.

**Physics Forums | Science Articles, Homework Help, Discussion**