Find the directional derivative of f(x,y,z)=xyzf(x, y, z) = xyzf(x,y,z)=xyz at (1,1,1)(1, 1, 1)(1,1,1) in the direction v=⟨1,1,1⟩\mathbf{v} = \langle 1, 1, 1 \ranglev=⟨1,1,1⟩.
111
3\sqrt{3}3
333
1/31/\sqrt{3}1/3