Task: Find a potential function for the conservative vector field (y,x,1) My work: (Df/Dx, Df/Dy and Df/Dz are the partial derivatives) Df/Dx=1, Df/Dy=x, Df/Dz=1 I take the first eq. and integrate, so that I get f(x,y,z) = yx + C I then derivate with respect to y: Df/Dy= x + C ' I compare this to the other eq. Df/Dy=x, hence C ' is 0, and consequently C is also 0. My answer is then f(x,y,z)=yx Which is wrong! Correct answer is yx+z. Where do I fail?