Find the directional derivative of f(x,y)=x+yf(x, y) = x+yf(x,y)=x+y at (0,0)(0,0)(0,0) in the direction of u⃗=⟨12,12⟩\vec{u} = \langle \frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}} \rangleu=⟨21,21⟩.
2\sqrt{2}2
111
000
12\frac{1}{2}21