Given f(x,y)=x2+y2f(x, y) = x^2 + y^2f(x,y)=x2+y2, find the directional derivative of ∇f\nabla f∇f at (1,1)(1, 1)(1,1) in the direction u⃗=⟨12,12⟩\vec{u} = \langle \frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}} \rangleu=⟨21,21⟩.
2\sqrt{2}2
222\sqrt{2}22
222
444