given that f(x,y) =(x^3 +y^3) ^(1/3). determine whether fy(0,0) exist?
i differentiated wrt to y, and then sub in (0,0) and i got that fy=0.
but my answer says that fy exists...
Well, what is a derivative? A derivative will tell us the slope of the tangent to the curve at a given point. Let me ask you this, can we have a horizontal tangent to the curve (i.e. no slope) and if we can, does this still "exist"?