I believe the average rate of change is given by:
I believe the instantaneous rate of change is given by the directional derivative. If , then the directional derivative is given by:
Another one I'm currently stuck on:
"Let f(x,y)=x^2+ln(y). Find the average rate of change of f as you go from (3,1) to (1,2). Find the instantaneous rate of change of f as you leave the point (3,1) heading toward (1,2)."
What exactly am I supposed to do in order to solve this problem?