1. The problem statement, all variables and given/known data .pdf file of assignment is here: http://www.math.washington.edu/~sullivan/3264_sp10.pdf So, I have a few questions about the assignment. Problem #1 I need to know how to find the 14 points. Problem #2 When it tells me to computer ∂f/∂x amd ∂f/dy at (0,0), does that mean I just I take the limit as (x,y)-->(0,0), since obviously the two are undefined at (0,0)? Problem #3 The two conditions for differentiability at a point are that f(x,y) is continuous at that point and that lim (h,k)-->(0,0) |f(x+h,y+k)-f(x,y)-(Ah+Bh)| / √(x2+y2) = 0, where A= [f(x+h,y)-f(x,y)]/h, B=[f(x,y+k)-f(x,y)]/k, according to my textbook. Right? How am I supposed to show that such approaches 0 is h,k approach zero? 2. Relevant equations They're scattered around the assignment 3. The attempt at a solution The only one worth showing my work is Problem 1. I used the theorem on the front. grad(F)=<1, 3y2, z3> grad(G)=<x2, y2, z2> grad(F), then, is never the zero vector. grad(G) is at the point (0,0,0). If I make grad(F) a scalar multiple of grad(G), my system of equations looks like 1=ßx2 3y2=ßy2 z3=ßz2 x2+y2+z2=1. ------> 1/ß + y2 + z3/ß = 1 -----> ß2 + 3y2 + ßz2=1. Now, how do I solve for the 13 other points with that equation???? Thanks in advance.