Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Calc 3 directional derivative question

  1. Oct 22, 2005 #1
    The question asks:
    Find the directional derivative of f (x, y, z) = z ln (x/y) at (1, 1, 2) toward the point (2, 2, 1).

    What I did was find the distance between the two points to be the directional vector (i+j-k) and then I took the norm of the direction vector. so my unit vector = 1/sqrt(3) * u; then I found the gradient. From there, I found the scalar product of my unit vector and the gradient to get 0. Did I approach this problem right? Does that answer seem correct to you?
     
  2. jcsd
  3. Oct 23, 2005 #2

    TD

    User Avatar
    Homework Helper

    Seems allright to me :smile:
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook