Finding the instantaneous velocity of a scalar function?

[supermiedos]

Homework Statement

Find the instantaneous velocity of f(x, y, z) = xyz, at (1, 2, 1)

Homework Equations

The Attempt at a Solution

I think this problem our proffesor gave us wasn't formulated correctly. The only time when we calculated instantaneous velocity was when we had a vectorial function like r(t) = x(t) i + y(t) j + z(t) k.

I tried using dw, but it doesn't work since i don't know dx, dy or dz

 

[Dick]

Homework Statement

Find the instantaneous velocity of f(x, y, z) = xyz, at (1, 2, 1)

Homework Equations

The Attempt at a Solution

I think this problem our proffesor gave us wasn't formulated correctly. The only time when we calculated instantaneous velocity was when we had a vectorial function like r(t) = x(t) i + y(t) j + z(t) k.

I tried using dw, but it doesn't work since i don't know dx, dy or dz

No, I don't think the phrasing of the question makes much sense.

 

[Mark44]

Just to make sure, is there any information that you omitted, like values for dx/dt, dy/dt, and dz/dt? If not, then I concur with Dick.

 

[supermiedos]

I knew it! No, there's no more information. Only f and the point (1, 2, 1). Thanks!