Question

find the directional derivative of the function given by:f(x,y,z)= x^2+y^2+z at point (1,2,1) in direction of the vector a= i+J+k.

Answer 1

Get grad for the function
Dot it with a unit vector in the direction of the given vector.

Answer 2

i got 2x ,2y and 1 for the grad

Answer 3

i got this as my answer \[(2 x+4 y+1)/\sqrt(6) \]