I'm going through some solutions to past questions and in one solution it is written:
$$\nabla f(x(s,t),t)$$
What would this mean expanded out? I would've thought it meant, here $x$ is representing the position, so x would have $x,y,z$ components. Would the $s$ be included in the expanded expression?
EDIT: the solution states $\frac{df}{ds}=\frac{dx}{ds}\cdot\nabla f$, I was just abit confused as to how they arrived at this expression, I know theyve applied the chain rule but just wanted an explanation.