Need help on how to go about gradients and directional derivativves in calculus II

Question

anonymous · Answer

gradient = <fx , fy>
and the direction is the gradient dot it with the unit vector

anonymous · Answer

Perfect response and very apt...Please prove for me this$$Dyf(x) = \lim !0 f(x + y) 􀀀 f(x)  Do you really need \to calculate this for every Dyf(x) for all directions y?$$

anonymous · Answer

o man um.. sorry i dont think i can do this this, cant really understand it completely either. 
unfortunately i only learned the basics of multivariable calc, I hope theres someone who can help you, again sorry

anonymous · Answer

Ok but you did great and thanks for the apt response

anonymous · Answer

yea np im sure someone can help you ^^

anonymous · Answer

are you asking about calculating partials?

anonymous · Answer

as he said, find the gradient, find the unit vector in the direction you're interested in... dot them.

anonymous · Answer

Yes partials and understanding on directional derivative in N-dimensions