## Calculus (3rd Edition)

$$f_1(x,y,z)=xyz+1.$$ (Other answers are possible.)
To get an example of a potential function for the vector $\langle yz,xz,xy \rangle$, we add a constant to the function $f=xyz$. For instance, we can get the function: $$f_1(x,y,z)=xyz+1.$$