Answer:
0
Step-by-step explanation:
We are looking for the directional derivative of f at P in the direction of PQ.
First we compute
[tex]\nabla f=\langle yz\cos(xy),zx\cos(xy),\sin(xy)\rangle\\\nabla f(0,0,2) =\langle 0,0,0\rangle[/tex]
But if we dot any vector to the zero vector we always get 0. So the rate of change is zero.
