Math Help - Rate of Change

1. Rate of Change

Find the rate of change of f(x,y,z) = cos(xyz) - ln(yz) + y(e^x) at the point (0,1,-1) in the direction toward the point (2,2,1).

I'm not quite sure how to do this. I know I have to find the gradient of f(x,y,z) . But I don't know how to proceed after that.

2. I think this is directional derivative. So find the gradient then multiply by the dot product of the other vector.

Directional derivative - Wikipedia, the free encyclopedia